filled above its overflow opening for suitable water testing application_number US 49426500 A description turning first to fig3 a down pipe 19 is shown being connected to overflow elbow 20 modified to enable the practice of the present invention in comparing elbow 20 with elbow 18 of the prior art it is seen that threaded member 23 is shown protruding from elbow 20 within the confines of protrusions 4 emanating from elbow 20 as shown threads 23 can be produced by extruding elbow 20 as a single unitary plastic part or alternatively an insert such as shown in fig4 and 5 as element 41 can be solvent welded to element 20 as desired in continuing the practice of the present invention foam gasket 9 is then placed upon elbow 20 being centered by protrusions 4 located thereon as noted in fig3 b foam gasket 9 is intended to reside on the backside of tub 30 which in turn is provided with an opening enabling access to threaded member 23 working from the inner side wall of tub 30 capture nut 21 can then be screwed down upon threaded member 23 using threads 22 to match therewith alternatively the threaded member 23 could be formed with interior threads and the capture nut 21 with outer threads as further noted in reference to fig3 a capture nut 21 is provided with flange 24 further optionally being configured with holes 25 enabling a suitable wire tool not shown to be inserted within holes 25 for increasing torque rotation of capture nut 21 to enable the capture nut to compressively draw elbow 20 to tub 10 as shown in fig3 b to in effect tightly draw.