SEPARA TOR Field of the Invention This invention relates to a separator with an oedflow bypass, and rorte particularIy. but not exclusively, to a separator ifr floikwter wit an otiew bypass, Background of the Invention 10 It is known to provide a separator for separating solid or parties. late matter from stormWater. However, te applicant has identified that existing separators are not suitable for use in separating storlwater prior topassing into an undeqground water sto-age tank structure as they either have no bypass capability for dealing with overflow, or they have a bypass capability aich ixes und tired stomiwater 15 Underground water storage tank structures, particularly of, the kind formed of stacked plastic modules the same or sindar to those shown in Australian Patent No 724847 are typically not able to be readily cleaned of pollutants which may be contained in unff1k red stormwater, 20 Examples Of" the Present invention seek to provide ail improved separator for tiltering water passing into storage container Sumnmarytof the invention 25 In accordance ilth one aspect of the present invention, there is provided an apparatus for separating solid or particulaite matter front a flowing fid the apparatus including: an ilet for allowing unfiltered li'd to enter the apparatus; filter means for sepaa mateial from the unfiltered fhuld; a first outlet for delivering from the appara t us only flui fitered 30 b) said filter means; and a second outlet for delivering from the apparams only fluid uiltered by said iher means when a level of fluid in the apparatus exceeds a predetermined level; a diverter arranged in a weir-like configuration such that it normally diverts the unfiltered fluid from the inlet to the fisher means unnil blockage or resrction in the filter means relative to the fluid flow raises the level of thud at the diverter to said predetermined level determined b y an upp. level of the diverter. above vhi ch the fluid fron the inlet overflows the diverter bypassing the filter means aind flowing to the second outlet; the second outlet being aranged to p rovide a nondiltering path along. ich all 5 bypassed unfiltered fluid passes and to prevent ixing of the bypassed fluid with the filtered fluid and a flow sensor arranged to sense flw of fluid though the ust outlet and/or the second outlet, and to generate an aert to an operator wv hen mitenneofl 1 the apparatus is required based on flow sensed by tie flow sensor. Preferabl.v. the apparatus further includes a diverter, wherein an upper level of the diverter defines the predeternined level.. More preferahl Ih divecr is arranged such vb-.btrd d is diverted by the diverer to the fiter means to exit the first outlet when the leave of unfiltered fluid at the diverter is below the tpper level, and wherein 15 unfiltered fluid is allowed to flow over the diverter to bypass the filtermns and to exit the second outlet when the level of the unfiltered fluid at the diverter is above the upper levels In a preferred example, the filter means includes a separation. ihamiber into wrich, 20 in use of the apparatus, the unfiltered fluid S introduced by the diverter to estab~ish a ciacur I ov of fluid within the separation chamber suclh that solids or partdeuciauenatter of a predeternined size drop into a sunip below the separation chamber Preierably a wa of dhe separalion chamber includes a separation screen having a plurality of openings of a predeterimned size for preventing solid or particulate latter larger than that size from 25 passing outwardly through the separation screen so as to filter the fluId Preferabl. the apparatus is provided with a first flow sensor for sensing flow through the first oudet. Mr. preferahi. the apparatus is provided with a second fow sensor for sensing flow through the second outlf in one example, the apparatus activates 30 an indicator in response to the seen.n d fow sensr sensing flow through the second oeu.t so as to alert an operator that the apparatus ray reuire muaintenance. An output ot the first low sensor may be used to determine cause of foxy througIh the second outlet in accordance wvith another aspect of the present nventtott there Is provided anapparatus for paatn solid or pariculate matter from a fwngfluid the apparatus including: an inlet for allowing onfiltered fhid to enter the apparatus; a separation chamber into which, in use of the apparatus. the unfiltered fluid is introduced by a diverter to establish a circular 5 flow of fluid within the separation ctanber such that solids or particulate matter o1 a predetermined size drop into a suinp below the separation chamber; a wall of the separation chamber including a separation screen having a plundity of openings of a predeternned size for preventing solid or particulate matter larger tan that size from passing outwardly through the separation screen so as o iter Ilithud an outer 10 chamber arranged about the separation chamber and being accessible to fluid in the separation chamber only via the openings in the separation screen: a first outlet for allowing flow of fluid from the outer charnber to exit the apparatus .nd a second oudiet. separate frorn the first outlet for allowing unfiltered fluid to flow directly from the inlet to bypass the separation chamber and to exit the apparatus. wherein the diverter diverts 15 unfiltered fluid. into the separation chamber wen a. level of the fluid at the diverter is at or below a top level of the diverter so as to tionow a filtering path via the openings in the separation screen and througii the outer tabor 1o the first outlet, and wherein the diverter alows mfilered fuid to now over tie diverter ten the levO of the fluid at the diverotr is above the top level so as to follow a non fli g paih separate to the filtering pathi in O whc the unfltered Iuid bypasses he separation chamber and exits the apparatus through the second outlet; and wherein the apparatus father includes a flow sensor aiane.dT to sense flow of fluid through the first outlet anti/or the second outlet, and to generated alert to an operator when maintenance or the aipptariatus is required based on fow sensed by the nlow sensor. 25 In accordance with another aspect of the present invention, there is provided an apparatus tor separating solid or particulate matter from strrniwater flowing to a water storage container the apparatus including; an inlet adapted for fluid communication with a storniwater drainage conduit so as to, in use alow unfiltered storniwater to enter the apparatus fron the stornwater drainage condtut' a separation chamber into wih in use 30 of the apparatus, the unfiltered stormwater is introduced by a diverter to the separation chamberi a wall of the separation chamber including a screen having a plurality of openingss ofa predetermined size or preventing solid or particulate matter larger thanthat size from passing through the screen so as to fiter the stortwater a receig chamber ned on an opposite side of the screen relative to the separation chanber and being accessible to stonrIwater in the separation chamber only via the openings in the screen: a. first outlet adapted for fuid connriciration with the water storage container so as to, in use, allow flow ot stormwater tron the receiving chamber to exit the apparatus to the water storage container; and a second outlet, separate from the first outlet r alowing unfiltered stornnater to flow directly front the inlet to bypass the separation chamber and to exit the apparatus. wherein the iverter diverts unfiltered stornvatehr ino the separation chamber when a level of fhe s tormwater at the diverter is at or below a top level of the diverter so as to follow a filtering path via the openings in the screen and through the 10 receiving chanber to the first outlet, and wherein the divener allows unfiltered stormnwater to flow over the diverter when the level of the stornmater at the drverter is above the top level so as to follow a non-filtering path, separate to the filtering pab, in which the unfdtered stornwater bypasses the separation amber and exits the apparatus through the second outlet: and wherein the apparatus further includes, a flow sensor arranged to sense 15 flow of fluid through the first outlet and/or the second outlet, and to generate an alert to an operator when maintenance of whe apparatus is required based on flow sensed by the flow sensor. Preferably. the second outlet is in fluid communication with the storm water 20 drainage conduit, at a location downstream of theinlet for allowing unfiltered stormwater to exit the apparatus to the stornwater drainage conduit. Preferably, the apparatus is provided with a first flow sensor for senseig flow along the filtering path. More preferably, the apparats is provided with a second flow sensor for 25 sensing flow along the non-filtering path. in one example the apparatus activates an indicator in response to the second flow sensor sensing nlow alonz Inc non-litering path so as to alert an operator that the apparatus may require maintenance, An output of the first flw sensor mar be vised to determine cause of flow through along the nonfiltering path. 30 In accordance with yet another aspect of the present invention, there is provided an apparatus tor separating solid or particulate matter frnm storinwater supplied by a stormwater drainage conduit. including a diverter which diverts unfiltered stormINater from the conduct ino a separation chamber when a level of the stornwater at the dMverter is at or below a top level of the diverter so as to follow a fitering path via openings in a separation screen to a storage container via a first outet, and which diverter allows unfitered stormwater to flow over the diverter when the level of te stormwater at the diverter is above the top level so as to Polow a non-tllerinng p separate to the filtering pathn in 5 which the unfiltered stormwater bypasses the separate ion chamber and is retuind to the stomiwater drainage conut via a second outlet; wherein the apparatus further includes a flow sensor arranged to sense flow of fluid through the first oudet aridor the second oidtt and to generate an alert to an operator when maintenance of the apparatus is required based on Jovy sensed by the flow sensor, Rief Description of the Drawings The invention. is described by way of nonritin. example only, with reference to 15 the accompanying drawings in whic.h. Figure I is a cu-away view of a prior inline separator t: Figmue 2 is a cut-away view of another prior inlne separator unit; 2 0 Figure 3 is a top perspective cut-away view of the inline separator of Figure 2. sectioned in a plane transverse to the direction of storlmwater flow; Figure 4 is a top cross-sectional view of the separator showna in Figures 2 and 3; Figure 5 is a side cross-sectional view of the separator shown in Figures 2 to 4; figure 6 is a top cross-sectional view of a separator in accordance with an example of the present invention; 30 [lgre 7 is a side cross-sectional view of the separator of t'g ure 6. the section being taken along the line A" shown in Figure 6; Figure 8 is. a top cross-sectional view of the separator shown in Figures 6 and 7. Figure 9 is a. side view of a removable screen of the separator shown in Figures 6 to 8; and Figure 10 is side cross-sectional view if the separator shown in Figures 6 to 9, the section being taken along line "B" shown in Figure 8, 10 Detailed Description With reference to Figure I there is shown a previous inlie separator unit 10 which is adapted 'forplacenernt in a. storm drain win a single mranhe, The unit cornbines treatment and bypass capabilities to remove both fine and suspended solids along with oil, 15 grease. rubbish and debris. The unit 10 includes a channelling weir 12 which collects flow for entrance into a separation. chamber 14. A natural vortex in the separaitn chamber 14 separates suspended and fiue sediments to the centre of the chamber 14 for eventual settling in a stump 16 located below the diversion chamber I4 A separation screen 18 wich fons a wall of the separation chamber 14 is designed so as to avoid bokage. 20 Flow of stonwvvater through the separation screen 18 is discharged from the separator 10 via an outlet 20 after flowing beneath an oil hafe 22 which retains olwith n the unit 10. In the event of flows in excess of S0 cubic feet per second, flow is able to bypass the separation chamber so as to flow directly to the outlet 20. 25 The unit 10 reportedly removes 80 percent of total suspending' so lids as well as 00 percent of floatables and netarally buoyant material plus oil and grease. Due to the non blocking design of the screen 18 and the generally non-mechanical operation of the unit 10. it is a low maintenance treatment option requiring cleaning once annually to maintain its successful and efficient operation. 30 Figures 2 to 5 show another form of previous inline separator unit 24 which uses a iitniia induced vortex flow to eptdtegs pllutants organic soot/sedinent and Oils from stormwater, The unit 24 is fhrned of a polmer which makes it ight and easy to use .insotCe control applications and small catchments. The unit has an inlet 26 a diverter 28, a separation, chamber 30, an outer chamber 32which surrounds the separaton chamber 30t a sumup 34. and a single outlet 36. Operaton of the separator unit 24 is shown diagramnaticaliy in [gure 2 in which arrows are used to indicate flow of uid through the 5 unit 24. More spcificaly, flow of unfIered stormwerr through the inlet 26 is diverted by the diverter 28 into the separation chamiber30 'W. 28 is mosed so as to induce a clockwi$se vorte X flow within tie separation chamber 30 which causes separation of 10 suspended and lie sednents to the centre of the chmnber 30 1or eventual settling in the sump 34. Stormwater iltiered through the screen 38 of the separation eamber 30 flows into the outer chamber 32 to form an anticioekwse flow about the separation chamber 30 and upwardly to exit the unit 24 through the single outlet 36. 15 However, the appieant has idented that neither unit 10 nor unit 24 is suitable for use in separating stormwater prior to passing ianto an underground water storage tank structure of the type formed of stacked. plastic iodu -iles the same or similar to those disclosed in Australian Patent No. 721847 As is dfiieult to clean an unwerground water storage tank structure of this kind, the applict has identihed the n fr a 20 separator which wul not bypass unfiltered stornwater into thIe tanik strucnur in the event of overflow, whetbe that Overflow is caused as a result of blockage of the screen of the separator or simply excessive flow of storm wer at the inlet of the separator. The separator apparatus 40 shown in Figures 6 to 10 is adapted to enable bypass of 25 a fher element of the separator in the eventof overflow while ensuring that ony filtered storm water is outlet into the water storage container. The apparatus 40 includes an inlet 42 a diverter 44, a separation chamber 46 having a screen 48, a receiving chamber 50. a first outdet 52..and a second outlet 54, 30 The inlet 42 is adapted for fluid communication wih a stornwater drainage conduit so as to, in use, allow unfiltered stornwater o enter the apparatus 40 front the stormvater drainage conduit. In use of the apparatus 40, the unfitered storrnwater is introduced by the diverter 44 to the separation chamber 46 As a result of the diverter 44 leading tangentially into a waii 5'6 of the separation chamber 6, the urAtered ftuid intoduced by the diverter 44 is establihed in a Ocirular lwwithin he separation chamber 46 Owing to the circular flow of the stornnvate solids or particul't a- tte -of a predetermined size drop into a 5 umnp 58 below the separation chamber 46 as shown inFigure 7 by arrow 60 in a manner similar to that show in Figure 2, The screen 48 forms at least part of the wall 56 othe separation chamber 46 and has a plurahty of openings 62 of a predetermined size for preventing solid or particulate. 10 matter larger than that size fiomn passing outiwardly throighlt the separation screen 48 to the outer receiving chamber 50 Owing to geoneiry of the openings 62 and/or the circular flow of the stormwiater solid or ariculate matter \maler than the size of the openings 62 may also be prevented from passing outwardly thru the separation screen 48 to the outer receiving chamber 50, in this way, the stormwater which reaches the oter receiving 5 chamber 50 is fiflered, as the receiving chamber 50 is accessible to the stormnwater in the separation chamber 46 only via the apertures 62 in the separation screen 48. The first outlet 52 is adapted for fluid comnfntrnication with the water storage container so as to, in uoeallo m How of stonnwater fhom the receiving chamber S0 to exit 20 the apparatus 40 to the water storage container Ie first outet >2 is accessible to stornrater at ith intet 42 via only the apertures 62 n the screen 48, thus ensuing that all storurwater exiting to the watr storage container has been filtered, The second outlet 54 is separate to the fist outlet 52, and is a-rranged to allow 25 unfiltered stormwater to flow directy from the inlet 42 to bypass the separation chamber 46 and to exit the apparatus 401 so as to be returned to the stornnwater drainage conduit at a location downstream of the inlet 42, The diverter 44 is arranged in a weiriue configuration to divert unfiltered 30 stormwater front the inlet 42 into the separation chamber 46 when a level of the stormwvater at the diverter 44 is at or below a top level of the diverter 44, so as to f01lw a filtering oath 64 via the openings 62 ithe screen 48 ai through the receiving chamber 50 to the first outlet 52 hr the event of overflow, which may be caused by' either excessive flow of stornvater at the inlet 42 and/or hy blockage of the screen 48. the diverter 44 As unfiltered stornwater to How over the diverter 44 whnrhe level of the stormwater at the diverter A14 is above the top Kvel so as to follow a non-fihering path 66. which is separate t the itering path 64 and in -which thnftered stonwater bypasses the 5 separation chamber 46 and cxits the apparatus 40 through the second outle 54. The apparatus 40 may aiso be provided vit a flow sensor for sensing flow along the non-filtering path 66 and/or a flow sensor for sensing Bow along the filtering path 64. The flow sensors) may be in the formi of a previouIsly known type of sensor for sensing 10 fluid flow such as, for example a spindle which is rotated in response to flow Cxer t ing force on Ens (or the like) attached to the spindle. An indicator which mar be in the emin of an audible or visual alarm is activated in response to thIalo#t g the nonf-ilnn paith 66 being sensed so as to alert an operator that the apparatus 40 may require maintenance I this way, the operator is able to inspect the apparatus 40, and to clean the seeen 48 15 and/or the sump 58, "o restore effective operation of thap parats 40, Arn output of the flow sensor for sensing flow along the filtering path 64 miay be used to determine cause of flow along the non-filtering path 66, For example. flow along both the filterng path 64 and the non-filterng path 66 may indicat the cause of flow 20 along the non-tiltering path as being excessive flow at the inlet 26. whereas flow aong only the non-n ltering path may indicate blockage of the scre-n 38, The above apparatus 40 has been described by way of example only and moineiications are possible within the scone of the invention. For example, although the 25 apparatus 40 is described as being used in a stornmwater system it will be understood by those skilled in the art that the apparatus may also be used to separate otherids. The reference in this specification to any prior publication (or information derived rom ith or to any matter which is known, is not, and should not ie taken as an 30 acknowledgment or admission or any form of suggestion that that prior publication (or information derived from it? or known matter tornms part of the common general knowledge in the field of endeavor to whichh this specificanm relates Throughout this specification and the claims which follow, unless the context requires otherwise. the word -comprise" and variations such as "comnprse" and "comprising", wil be understood to imply the inclusion of a stated integer or step or group of integers or steps but not the exchisioni of any other integer or step or group of integers Or 5 steps.