GB2120545A

GB2120545A - A watertrap attachment for a sink etc. overflow

Info

Publication number: GB2120545A
Application number: GB08234356A
Authority: GB
Inventors: George Molyneux
Original assignee: Individual
Current assignee: Individual
Priority date: 1982-05-22
Filing date: 1982-12-02
Publication date: 1983-12-07
Also published as: GB2120545B

Abstract

The invention provides an attachment for fitting over the overflow opening 14 in a bath, washbasin or sink 10, for hygenic purposes, the attachment comprising an open- topped container 20 having an outlet communicating with the overflow opening, and a baffle 36 in the container which is so arranged, that a water trap is provided in the container. Hence, the water trap acts to seal the overflow passage from the interior of the room in which the bath, basin or sink is fitted. A reversible back sealer 44, which enables the attachment to be used with either a vertical wall or with a concave wall, is also provided. <IMAGE>

Description

SPECIFICATION An attachment for a sink The conventional bath, washbasin or sink (which are hereinafter all referred to as sinks) has a waste outlet, which can be closed by a plug, and an overflow arrangement, which has an overflow opening at a relatively high level within the sink.

The overflow arrangement essentially comprises a bypass of the waste outlet. It has been shown that the conventional overflow quickly becomes contaminated, and is a breeding ground for bacteria. The problem is mentioned in the Building Research Establishment Digest No. 15, reprinted in 1 973 (published by Her Majesty's Stationary Office) which at pages 4 and 5 contains the following passage: "The standard (i.e. B.S. 1188:1965) requires basins to be provided with an overflow to prevent flooding, so designed that it can be easily cleaned.

In practice this is very difficult to achieve and it is virtually impossible to clean the overflow on most basins; when the waste plug is opened the dirty water rises in the overflow passage leaving behind it a coating of scum which produces an unpleasant smell, particularly in warm weather, when various bacteria and fungi thrive in the damp and dark environment." Although sinks are now sometimes made without overflows, this is not a satisfactory solution, because there is then the danger of flooding, which the overflow was intended to avoid, or at least alleviate, in the first place.

It is the object of the present invention to reduce or eliminate the problem of unpleasant smells and potential health risk arising out of the difficulty of cleaning a sink overflow.

According to this invention an attachment for a sink (as herein defined) comprises an open-topped container adapted to be fitted in a sink, so as to cover an overflow opening in a substantially vertical wall of the sink, there being an outlet from the container for communication with the sink overflow opening, and a baffle in the container, so arranged relatively to the container outlet, that, when the attachment is in the operative position, the baffle and the container provide a water trap in the container, so that the overflow opening is completely sealed by the water trap. Water traps are known to be effective in the case of soil pipes for example, and a water trap in the inlet end of the sink overflow will be effective to prevent odours from the overflow entering the room in which the sink is located.The invention therefore is based on the novel conception of providing a water trap at the inlet to the overflow, or to express this conception another way, to provide a water trap on the inside of the sink protecting the inlet to the overflow.

In a preferred construction, the lower edge of the baffle is below the lower edge of the container outlet, so that the water trap will be provided irrespective of the vertical relationship between the container outlet and the overflow opening, when the attachment is in the operative position.

According to a preferred feature, there is also provided a back sealer adapted to be located on a back face of the attachment surrounding, but not substantially obstructing the overflow opening, and further adapted to engage with the substantially vertical wall of the sink, so as to form a seal between that wall and the attachment, the sealer having a substantially flat face and an opposite convex face, whereby in one orientation, it is adapted to seal on a substantially flat vertical wall and in the reversed orientation, it is able to seal in a concave vertical wall. This is a significant feature, because it is obviously desirable that the attachment should be useable in as many situations as possible, and some sinks have flat vertical rear walls, whereas others have concave vertical rear walls.

According to another preferred feature of the invention, the attachment is provided with a fastening device attached to the attachment, and extending rearwardly therefrom for insertion through the overflow opening, a rear portion of the fastening device being expansible by screw-andnut means, the screw head being accessible from the front of the attachment and the fastening device engaging with a part of the attachment in a manner to prevent rotation of the fastening device relatively to the attachment. With this preferred feature, it is a very simple matter to secure the attachment to a sink, and in particular, it is not required that the overflow opening shall be fitted with any kind of adapter (or even an overflow opening cover) so that the attachment can be utiiised where the sink overflow opening simply comprises a hole formed through the vertical wall of the sink.

An overflow attachment for use in a domestic washbasin, in accordance with the invention, will now be described by way of example only, with reference to the accompanying drawings, in which: Figure 1 is a cutaway perspective view showing an attachment in accordance with the invention mounted in a washbasin, Figure 2 is a vertical section through the attachment, Figure 3 is a front view of the attachment looking in the direction of arrow Ill in Figure 2, Figure 4 is a rear view of the attachment looking in the direction of arrow IV in Figure 2, but with the rear wall removed, Figure 5 is a plan view of the attachment, Figure 6 is a front view of a reversible back sealer, Figure 7 is an end view of the back sealer looking in the direction of arrow VII in Figure 6, Figure 8 is a plan view of the back sealer, Figure 9 is a side view of a fastener, Figure 10 is a plan view of the fastener shown in Figure 9, and Figure 11 is a vertical section through the attachment showing it fitted in a washbasin.

Part of the rear wall of a typical ceramic washbasin is shown at 10 in Figures 1 and 11.

The washbasin illustrated is of a well known construction, in which, in order to provide an overflow arrangement, a hollow chamber 1 2 is formed integral with the rear wall of the basin in a central region of the rear wall, there being a generally rectangular overflow opening 14 through the rear wall into the upper part of the chamber 12, and the lower end of the chamber (not shown) being connected to the washbasin waste pipe below the drain outlet in the bottom of the basin. If the level of water in the basin rises above the bottom edge 15 5 of the overflow opening 14, then water flows through that opening and via the overflow chamber 12 into the waste pipe.In theory, the overflow passage provided by the opening 14, the chamber 12 and the connection to the waste pipe should be capable of taking the full flow through the tap or taps feeding into the washbasin, to ensure that there cannot be overflow of water from the washbasin into the room in which the basin is placed.

In the washbasin illustrated, the rear wall 10 is vertical, but it is rearwardly concave (i.e. as seen in plan it is curved, with the centre to the rear of the ends).

In many modern installations, the overflow passage takes the form of a flexible plastics pipe, which is attached to the rear of the rear wall 10 of the washbasin, the overflow opening 14 leading into the inlet end of the overflow pipe.

In any event, whatever type of overflow passage is provided, there is always the problem, that it is exceedingiy difficult to clean the interior of this passage. This mainly arises out of the fact that the opening 14 is in a substantially vertical wall of the washbasin, whilst the overflow passage itself extends generally in a vertical direction. Also, some waste water from the washbasin sometimes builds up in the lower part of the overflow passage, when the washbasin is being emptied. This is because once the waste water from the basin fills the waste pipe down to the U-bend in the waste pipe, there is then some restriction on the waste outlet flow, which causes the build-up of waste in the overflow passage.

This waste water is usualiy dirty, and when it flows out of the overflow passage, it leaves behind it a film of dirt on the inside of that passage.

Consequently, the overflow passage is nearly always dirty, and frequently is a breeding ground for bacteria and fungi. Hence, there is a tendency for objectionable odours to be emitted from the opening 14 into the washbasin, and in some cases, this can be a danger to health.

The attachment provided by the invention essentially comprises an open-topped container or trough 20 having closed ends, and moulded in plastics material (though for cleaning purposes and aesthetic reasons, the attachment may be coated with a chromium film). As illustrated in Figures 1 and 11, the trough 20 is adapted to fit against the front of the rear wall 10 of the washbasin in a position where it encloses the overflow opening 14. Referring now to Figures 2 to 5, the container 20 has a front wall 22, which curves rearwardly at each end to provide end walls 23 to close the ends of the trough. The front and end walls of the trough merge into a bottom 24. A recess 26 is formed in the rear edge of the bottom 24, and this recess is also continued into the rear edges of the end walls of the trough - see Figure 4.This recess provides a location for an upstanding rear wall 28 which is mouided in the same material as the remainder of the container 20, and welded in the recess 26 by ultra-sonic welding. Thus, the rear wall 28 forms an integral part of the container and it is only made separately to ease the moulding of the container itself. It will be observed that the rear wall 28 is not so high as the front wail 22, so that the effective depth of the trough is that from the bottom 24 to the top edge of the rear wall 28.

The rear wall has a rearwardly projecting lip 30 along its upper end, and there is a recess 32 open on the rear side immediately below the lip 30.

Each end wall 23 has a rearward upper extension 25, so that the rear edges of the walls 25 are in the same vertical plane as the rear edge of the lip 30, and there is a cap 34 extending across the top of the end walls 25 and having its rear edge in the same plane as the rear edges of the end walls 25.

A baffle 36 crosses between the front edges of the upper end walls 25 and depends into the trough formed by the container 20.The ends of the baffle merge into the end walls 23 of the trough. It will be noted that the baffle 36 is approximately midway between the front wall 22 and the rear wall 28 and that its lower edge 39 is below the top edge of the rear wall, i.e. it dips into the effective trough. Figure 5 shows that the front wall 22 is bowed slightly forwardly and the baffle 36 is similarly forwardly bowed, but this is merely for the sake of appearance.

In use, the attachment which is illustrated in Figures 1 to 5 has to be placed against the rear wall 10 of the washbasin, in a position where it surrounds the overflow opening 1 4. Moreover, it is important that the attachment should seal against the rear wall 1 0. Clearly, there would be problems in attempting to provide such a seal, if one had to rely on merely pressing the rear edges formed on the cap 34 the end walls 25 and the lip 30 into engagement with the front surface of the rear wall 1 0. However, there is also provided the reversible back sealer 44, which is illustrated in Figures 6 to 8. This back sealer is intended to be located between the attachment 20 and the rear wall 10, as illustrated in Figure 1, and it is made in a medium density polyethylene, or any other resilient and slightly deformable material.

As is shown in Figures 6 to 7, the back sealer 44 generally takes the form of a rectangular frame having a large rectangular opening 46 formed therethrough, the size of this opening being somewhat larger than the largest washbasin overflow, which is likely to be encountered in practice. Washbasin overflows vary somewhat in dimensions, but in a typical example, the opening 46 has a length of 3 inches, and a width of three quarters of an inch, and it has been found that a back sealer with an opening of these dimensions can be utilised with the great majority of washbasin overflow openings as used in the United Kingdom at the present time. It will be appreciated of course, that the dimensions of the attachment 20 itself, and the corresponding dimensions of the back sealer 44, will have to be adapted to the likely dimensions of overflow openings as used in any particular country.

There are two bridge pieces 48 formed across the rectangular opening 46, but these are merely provided to give the sealer rigidity, and otherwise they should be as small as possible, so that they offer a minimum resistance to water flow through the opening 46. It is also important for present purposes, that the bridge pieces 48 should be spaced on opposite sides of the centre region of the sealer.

The sealer has a top wall 50, a bottom wall 52, and end walls 54. These are all of the same thickness, and the bottom wall 52 should be able to fit snugly in the recess 32 formed in the rear wall 28 of the attachment 20. Further, the internal dimensions of the walls 50, 52 and 54 should be such, that the rear edges of the walls 25, the cap 34 and the lip 30, can be received snugly within the walls on the back sealer, as illustrated in Figure 1. It will be appreciated, that when the sealer 44 is placed on the rear of the attachment 20, as illustrated in Figure 1, it is retained thereon by friction, and when the attachment 20 and the sealer 44 are then offered up to the rear wall 10 of a washbasin, it is possible to trap the sealer 44, between the attachment 20 and the rear wall, so that the sealer 44 provides the required effective seal between the attachment and the rear wall 10.

In practice of course, the attachment is placed in a position such that the opening 46 through the sealer is in alignment with the overflow opening 14 in the washbasin, so that the upper part of the attachment 20 completely surrounds the overflow opening 14 on the front side.

Referring now to Figure 8, one edge of each of the top and bottom walls 50 and 52 is straight, but the opposite edge 58 is convex (i.e. bowed outwardly at the centre). In Figures 1 and 11, the front face of the rear wall 10 of the washbasin, is illustrated as being curved. In that case, the straight walls 50 and 52 of the sealer 44 are engaged respectively on the cap 34 and the lip 30 of the attachment 20, so that the effective rear edge of the sealer 44 is curved, for snug fitting against the front face of the wall 10. (If the washbasin is of lye type where the rear wall 10 is flat, then the sealer 44 is fitted on to the attachment 20 in the reverse orientation -- that is to say the curved edged portions of the walls 50 and 52 are engaged on the attachment, the wall 52 then engaging in the recess 32, so that it is the straight edges 56 which form part of the rear surface of the sealer.) Clearly, the bowed edges 58 will not always fix exactly to the bowed surface in the washbasin, but any slight difference can be taken up, by compression of the sealer 44.

It will be appreciated therefore, that before the attachment 20 can be fitted inside a washbasin, the user has to determine in which orientation to employ the back sealer 44, but as there are only twd possibilities, this is a very simple choice, particularly, since it will become immediately obvious, if the wrong decision has been made.

It is also necessary to be able to secure the attachment inside the washbasin, in a simple manner, and for this purpose, a fastening device 60 (see particularly Figures 9 and 10) is provided.

The fastening device is also made as a moulding in medium density polyethylene, and it generally takes the form of an elongate square section rod.

The main or forward portion 62 of the fastener has a series of transverse grooves 64 formed in its top and bottom surfaces near to its rear end, and this forward portion 62 is bifurcated by a slit 66 from the rear end, there being a stress relieving hole 70 at the front end of the slit 66. Moreover, the slit 66 is flared outwardly at the rear end, to provide curved rear surfaces 70 on the bifurcated portion, and there is a circular hole 72 formed through the length of the forward portion 62.

A rearward portion 74 of the fastener 60 is of much shorter length than the forward portion 62, but is generally of the same cross-section. It is joined to the forward portion by top and bottom temporary retaining strips 76, which can be relatively easily torn, to detach the rearward portion 74 from the forward portion 62. A rectangular slot 78 extends into the rearward portion 74 from one side thereof, and the hole 72 is continued through the rearward portion 74. The front end of the rearward portion 74 is pointed, as illustrated at 80, the converging top and bottom sides of this pointed portion 80 being parallel with the curved outwardly flared surfaces at the rear end of the bifurcated part of the forward portion 62.

The apparatus is completed by a long setscrew 82, shown only in Figure 11, and a hexagon nut 84 for co-operation with the setscrew 82. The slot 78 is of such dimensions, that when the nut 84 is pressed into it, it cannot rotate therein, and the hole 72 is a clearance hole for the setscrew 82.

Furthermore, the external dimensions of the fastening device 60, are such, that its forward end can be received in the pocket 38 formed on the rear of the baffle 36, but when so received, the fastening device cannot rotate relatively to the baffle.

Finally, a lug 88 projects from the bottom 24 of the attachment, and a hole 90 is formed through this lug. The lug 88 is provided in case it is necessary to attach the drain plug chain to the attachment, although this method of securing the drain plug chain is not illustrated.

When it is required to fit the attachment inside a washbasin, the sealer 44 is first fitted on to the rear of the attachment, the orientation of the sealer being selected in accordance with the shape of the rear wall 10 of the washbasin, as previously described. The fastening device 60 is engaged in the pocket 38 - see Figure 11 - and the screw 82 is threaded the hole 42 in the baffle 36, then through the hole 70 in the fastening device 60, and into threaded engagement with and through the nut 84. Then the rear end of the fastening device is threaded through the overflow opening 14, and the attachment is adjusted into a position, where it completely covers the overflow opening 14. It is then possible to secure attachment in this position, by turning the screw 82, and this is facilitated by the provision of the notch 82.Because the nut 84 cannot rotate, and the fastening device itself cannot rotate in the pocket 38, the rearward portion 74 of the fastening device is drawn forwardly, and its wedge-shaped front portion 80 engages in the slit 66. Further forward movement of the rearward portion 74 causes the bifurcated sections of the forward portion 62 of the fastening device to be expanded, and eventually, the temporary retaining strips 76 are torn, so that the rearward portion 74 becomes detached from the forward portion. By that time however, the rearward portion is tightly engaging in the bifurcated part of the forward portion, and therefore the rearward portion 74 is still prevented from rotation. The outward expansion of the bifurcated part of the fastening device has the effect of engaging that part with the rear inside edges of the overflow opening 14, as illustrated in Figure 11.In this way, the attachment 20 becomes firmly secured to the rear wall 10 of the washbasin, and the back sealer 44 is placed under sufficient compression, to ensure the necessary seal.

The location of the attachment 20 will probably be such that the top edge of the back wall 28, will be below the top edge 1 5 of the overflow opening 14, which determines the level at which overflow can take place. However, the precise location of the wall 28 relatively to the opening 14 is not critical, although if the top edge of the back wall 28 is above the level of the edge 15, then it will be the top edge of the back wall, which will determine the level at which overflow will takeplace.

Taking the position illustrated in Figures 1 and 11, if water is poured into the attachment 20 through the opening between the front wall 22 and the baffle 36, that water will build up in the effective trough, and will eventually overflow over the weir created by the edge 15, down into the overflow passage. This therefore determines the level of water in the trough provided by the attachment, and this level will always be above the bottom edge of the baffle 36, even in the case, where the level of the water is determined by the top edge of the back wall 28. Hence, a water trap is formed in the attachment 20, and communication between the interior of the washbasin and the overflow passage can only be obtained through this water trap.Hence, there is no possibility of odours or gases from the interior of the overflow passage passing out through the attachment into the room in which the washbasin is provided. This provides an obvious hygienic advantage, and obviates a likely cause of undesirable smells in the room. Moreover, it is possible to pour a detergent and/or a disinfectant into the trough, so that the liquid which is visible in the trough will not itself give off any objectionable odour. Every time additional water is poured into the attachment (either deliberately for cleaning purposes, or if there is an overflow from water in the washbasin out through the overflow passage) the detergent and/or disinfectant contained within the trough will be washed down the overflow passage, and this has a cleaning effect.However, it will be appreciated, that because of the complete seal provided by the water trap, it is no longer vital to clean the inside of the overflow passage, and indeed, that passage could be regarded as part of the drain system, which is sealed by water seals from the interior of the room in which the washbasin is located.

The entire attachment, including the back sealer, is of relatively small compass, and in particular, projects only a short distance into the useful area of the washbasin. In practice, it has been found possible to make the attachment project by such a short distance, that it makes no practical difference to use of the washbasin.

Indeed, the attachment is contained in an area of the washbasin, to which access is normally restricted in any case, by the overhanging tap or taps. This is particularly the case, where there is a single central tap.

As is illustrated in Figure 11, it is possible to take the ordinary drain plug 92, when that plug is not in use, and locate it in the opening provided between the baffle 36, and the front wall 22. One of the problems of a washbasin unit, is that there is normally no parking place for the drain plug, excepting the ordinary soap tray. Hence, it is an additional advantage of the attachment provided by the invention, that a parking place is provided for the drain plug, whereby the piug can be kept in an unobtrusive position, when it is not in use.

Moreover, the drain plug chain 94, or at any rate that part of the chain which is normally immersed in water within the washbasin, can be stored in the container provided by the attachment 20. If the water in the trough includes a detergent and/or disinfectant, the chain 94 will be cleaned each time it is stored within the trough. This is an additional advantage, because in practice, it is also quite difficult to clean that part of the chain which is normally immersed in the water in the washbasin. As previously explained, if there is no anchoring point for the chain on the washbasin, it is possible to anchor it to the lug 88 provided on the attachment.

In the construction which has been illustrated, there is a back wall 28. It might be possible in some circumstances, to omit this back wall altogether, and to fit the attachment to the rear wall of the washbasin, in such a way, that the rear wall of the washbasin itself is used to provide the effective back wall of the trough which is an essential to the formation of the water trap.

In some instances, particularly some baths, the overflow outlet is protected by a metal cap (or a plastics cap coated with chromium), there being a series of holes formed through the cap. Very often, in that case, the drain plug chain for the bath is attached to the centre of the cap covering the overflow opening. It is still possible to utilise the present invention, but of course the attachment which is provided must then be shaped, so that it can be located on the cap. Further, it will be necessary to offset the location of the fastening device, to ensure that it can be inserted through one of the available holes through the overflow cap. Indeed, it will readily be appreciated, that the attachment could be designed to fit on any type of overflow opening, but the design which is illustrated in the drawings, is quite versatile, in relation to the generally rectangular overflow openings which are found in the majority of washbasin and sink units.

Claims

CLAIMS 1. An attachment for a sink (as herein defined) comprising an open-topped container adapted to be fitted in a sink, so as to cover an overflow opening in a substantially vertical wall of the sink, there being an outlet from the container for communication with the sink overflow opening, and a baffle in the container, so arranged relatively to the container outlet, that, when the attachment is in the operative position, the baffle and the container provide a water trap in the container, so that the overflow opening is completely sealed by the water trap. 2. An attachment as claimed in Claim 1, in which the lower edge of the baffle is below the lower edge of the container outlet, so that the water trap will be provided irrespective of the vertical relationship between the container outlet and the overflow opening when the attachment is in the operative position. 3. An attachment as claimed in Claim 1 or Claim 2, also comprising a back sealer adapted to be located on a back face of the attachment surrounding, but not substantially obstructing the overflow opening, and further adapted to engage with the substantially vertical wall of the sink so as to form a seal between that wall and the attachment, the sealer having a substantially flat face and an opposite convex face, whereby in one orientation it is adapted to seal on a substantially flat vertical wall and in the reversed orientation, it is able to seal on a concave vertical wall. 4. An attachment as claimed in any one of Claims 1 to 3, which is further provided with a fastening device attached to the attachment and extending rearwardly therefrom, for insertion through the overflow opening, a rear portion of the fastening device being expansible by screw-andnut means the screw head being accessible from the front of the attachment and the fastening device engaging with part of the attachment in a manner to prevent rotation of the fastening device relatively to the attachment. 5. An attachment as claimed in Claim 4, in which the fastening device is of rectangular crosssection and its front end is received in a correspondingly shaped pocket on the rear of the baffle. 6. An attachment as claimed in any one of Claims 1 to 5, in which the spacing between the baffle and the front of the container is such that a drain plug can be located in it. 7. An attachment for a sink, constructed and arranged substantially as herein described with reference to Figures 1 to 5 of the accompanying drawings. 8. An attachment as claimed in Claim 7, having a reversible back sealer constructed and arranged substantially as herein described with reference to Figures 6 to 8 of the accompanying drawings. 9. An attachment as claimed in Claim 7 or Claim 8, having a fastening device constructed and arranged substantially as herein described with reference to Figures 9 to 11 of the accompanying drawings. 10. A sink, as herein defined, having an overflow opening in a substantially vertical wall, covered by an attachment in accordance with-any one of Claims 1 to 9. New claims or amendments to claimed filed on 28:6:83 Superseded claims: all New or amended claims:-

1. An attachment for a sink (as herein defined) comprising an open-topped container adapted to be fitted in a sink, and having a rear wall for covering an overflow opening in a substantially vertical wall of the sink, there being an outlet opening from the container in the rear wall for communication with the sink overflow opening, the effective lower edge of the outlet opening forming a weir, and a baffle in the container so arranged relatively to the container outlet opening, that, when the attachment is in the operative position, the baffle and the container provide a water trap in the container, so that the overflow opening is completely sealed by the water trap, the outlet opening occupying substantially all the available space in the rear wall above the weir so that the outlet opening is of maximum size in relation to the size of the container.

2. An attachment for a sink (as herein defined) comprising an open-topped container adapted to be fitted in a sink, so as to cover an overflow opening in a substantially vertical wall of the sink, there being an outlet from the container for communication with the sink overflow opening, the container construction ensuring the provision of a horizontal weir over which water leaving the container has to flow when passing through the outlet and a baffle in the container, so arranged relatively to the container, that when the attachment is in the operative position, the baffle and the container provide a water trap in the container, so that the overflow opening is completely sealed by the water trap.

3. An attachment as claimed in Claim 1 or Claim 2, in which the lower edge of the baffle is below the lower edge of the outlet, so that the water trap will be provided irrespective of the vertical relationship between the container outlet and the overflow opening when the attachment is in the operative position.

4. An attachment as claimed in any one of Claims 1 to 3, also comprising a back sealer adapted to be located on a back face of the attachment surrounding, but not substantially obstructing the overflow opening, and further adapted to engage with the substantially vertical wall of the sink so as to form a seal between that wall and the attachment, the sealer having a substantially flat face and an opposite convex face, whereby in one orientation it is adapted to seal on a substantially flat vertical wall and in the reversed orientation, it is able to seal on a concave vertical wall.

5. An attachment as claimed in any one of Claims 1 to 4, which is further provided with a fastening device attached to the attachment and extending rearwardly therefrom, for insertion through the overflow opening, a rear portion of the fastening device being expansible by screw-andnut means the screw head being accessible from the front of the attachment and the fastening device engaging with part of the attachment in a manner to prevent rotation of the fastening device relatively to the attachment.

6. An attachment as claimed in Claim 5, in which the fastening device is of rectangular crosssection and its front end is received in a correspondingly shaped pocket on the rear of the baffle.

7. An attachment as claimed in any one of Claims 1 to 6, in which the spacing between the baffle and the front of the container is such that a drain plug can be located in it.

8. An attachment for a sink constructed and arranged substantially as herein described with reference to Figures 1 to 5 of the accompanying drawings.

9. An attachment as claimed in Claim 8, having a reversible back sealer constructed and arranged substantially as herein described with reference to Figures 6 and 8 of the accompanying drawings.

10. An attachment as claimed in Claim 8 or Claim 9, having a fastening device constructed and arranged substantially as herein described with reference to Figures 9 to 11 of the accompanying drawings.

11. A sink (as herein defined) fitted with an open-topped container covering an overflow opening in a substantially vertical wall of the sink, there being an outlet from the container communicating with the sink overflow opening, and a baffle in the container, so arranged relatively to the container outlet, that the baffle and the container provide a water trap in the container, so that the overflow opening is completely sealed by the water trap.

12. A sink as claimed in Claim 1 in which the lower edge of the baffle is below the lower edge of the container outlet, so that the water trap is provided irrespective of the vertical relationship between the container outlet and the overflow opening.

13. A sink as claimed in Claim 11 or Claim 12, in which a back sealer is located on a back face of the container surrounding, but not substantially obstructing the overflow opening, and engaging with the substantially vertical wail of the sink so as to form a seal between that wall and the container, the sealer having a substantially fiat face and an opposite convex face, whereby in one orientation it is adapted to seal on a substantially flat vertical wall and in the reversed orientation, it is able to seal on a concave vertical wall.

14. A sink as claimed in any one of Claims 11 to 13, in which the open-topped container is further provided with a fastening device attached to it and extending rearwardly therefrom through the overflow opening, a rear portion of the fastening device being expansible by screw-andnut means the screw head being accessible from the front of the container and the fastening device engaging with part of the container in a manner to prevent rotation of the fastening device.

1 5. A sink as claimed in Claim 14, in which the fastening device is of rectangular cross-section and its front end is received in a correspondingly shaped pocket on the rear of the baffle.

16. A sink as claimed in any one of Claims 11 to 15, in which the spacing between the baffle and the front of the container is such that a drain plug can be located in it.

1 7. A sink with an open-topped container constructed and arranged substantially as herein described with reference to Figures 1 to 5 of the accompanying drawings.

18. A sink fitted with an open-topped container having a reversible back sealer constructed and arranged substantially as described with reference to Figures 6 to 8 of the accompanying drawings.

19. A sink fitted with an open-topped container as claimed in Claim 17 or Claim 18, having a fastening device constructed and arranged substantially as herein described with reference to Figures 9 to 11 of the accompanying drawings.

20. A sink as herein defined, having an overflow opening in a substantially vertical wall, covered by an attachment in accordance with any one of Claims 1 to 10.