A running bill that does not match the site measurement

Measure item by item; never accept a lump figure.

• Main drain: the six cubicles sit at 1.2 m centres, so from the first WC to the last WC the run is 5 spacings x 1.2 m = 6.0 m. Add the 4.0 m from the last cubicle to the inspection chamber: main drain = 10.0 m.
• Branches: 6 branches x 0.9 m = 5.4 m.
• Vent stack: 7.5 m, as stated, including the 2 m above roof.
• Sub-total laid length: 10.0 + 5.4 + 7.5 = 22.9 m.
• Wastage and cutting allowance: for PVC pipe with many short branches, 5–10 per cent is normal. At 7.5 per cent that is about 1.7 m, giving 24.6 m.
• Ordered in 6 m lengths: 24.6 / 6 = 4.1, so 5 lengths = 30 m. Even at a generous 10 per cent wastage the requirement is about 25.2 m, still 5 lengths.

Conclusion: the site measurement supports about 23–25 m of pipe, or at most 30 m supplied. The claim of 42 m is roughly 17 m more than the work can possibly contain - about four extra lengths. That is not a rounding difference; it is a measurement that cannot be reconciled with the drawing.

What to record: the measurement in the measurement book item-wise (main drain, branches, vent), the basis of the wastage percentage, the drawing and specification reference, and the date of measurement with your signature and the contractor's counter-signature on the corrected figure. Photograph the run with a tape visible at one or two places, and note the slope actually measured against 1 in 60 - the fall from the first WC to the chamber invert is about 167 mm over 10 m, and if the chamber is shallower than that, the item needs a recorded variation, not a silent one.

Payment certifies quality and compliance as well as quantity. Work through the following:

1. Pipe class and marking. Look for the 3 kg/cm2 marking and the manufacturer's name on the pipe left on site and, where visible, on the installed pipe. Two classes of 110 mm pipe look almost identical but differ in wall thickness and price - this is the commonest substitution in school work.
2. Gradient. Measure the invert level at the first WC and at the chamber with a level or a hose-and-staff, and check the fall against 1 in 60 over the measured run. A flat line passes a quick visual check and chokes within a year, and it is invisible once the floor is laid.
3. Joints and bedding. Sockets should face upstream, joints should be fully home with no gap or cement smear inside, and the pipe should be bedded in sand with haunching, not lying on rubble or touching the trench bottom only at the sockets.
4. Vent termination. Confirm the stack really does go 2 m above the roof and is not cut off in the ceiling void or below a window; measure it, do not take a photograph from the ground as proof.
5. Inspection chamber and covers. FRP covers as specified, correct invert benching, channels formed and smooth, and a sealed frame. A broken or substituted cover and a badly benched invert are both classic 'looks complete' defects.
6. Testing. Insist on a water test: charge the line and hold, and a smoke or air test on the branches, with the results entered in the record. Without a test there is no evidence that the joints are sound.
7. Restoration. Floor finish, plinth protection and making good around the chambers.

Any item that fails is recorded as a defect with a date for rectification, and the corresponding value is held back - not deducted permanently, but not certified either.

This is the judgement the exam is really testing: a false measurement is fraud, whatever the intention and whoever asks for it. Signing the book certifies that you measured 42 m and found it laid. You did not. If you sign, you have personally certified a false record for a public body, and the 'adjustment next bill' is a promise with no value: the next bill may never come, the contractor may change, and the file will show your signature. The school's money is public money, and the headmaster's friendliness is not authority to misstate it.

What to do, in order

1. Do not sign the book as presented. Say this plainly and early, in front of the contractor if possible, so there is no private negotiation.
2. Offer the legitimate route to the deadline. Measure the work properly, correct the bill to the measured quantity (about 23–25 m), get the contractor's counter-signature on the corrected measurement, and forward it with a covering note explaining the correction. A corrected bill can usually be cleared within days - the financial year is not a reason to certify a wrong figure. If some items are disputed, certify the undisputed value and record the balance as held, which still releases most of the payment.
3. Record the reason in writing. A one-paragraph note that the measured length is 23–25 m against a claimed 42 m, with your working, protects you if the contractor complains later and gives the headmaster something factual to forward.
4. Refuse the offer, without drama. 'Adjusting in the next bill' is not a correction, it is a second false entry. Say you will not carry an unreconciled figure forward, and that any extra work actually done must be measured and sanctioned as an extra item before it is paid.
5. Escalate if pressed. If the headmaster insists, refer the matter to the departmental officer or the school management committee in writing. Being asked to sign a false measurement is itself something to report, not something to absorb quietly.

The professional line: a plumber's reputation is his measurement book. A supervisor who signs 42 m for 24 m of pipe will be believed on nothing afterwards, and in a public works job he is also exposed to audit objection and recovery.