Quotation for a School Toilet Block with a Site Measurement Conflict
A Zilla Parishad primary school in Aurangabad district has approved a toilet block with 8 WC units (4 boys, 4 girls), 8 wash basins and 6 urinals. The plumbing drawing shows a 25 mm CPVC cold-water branch to the last WC as 3.0 m from the main, but on site the average branch runs 4.2 m because of a column. The main run is 18 m and the riser is 12 m. Each fixture point needs 2 elbows and 1 tee. The plumber's labour rate is ₹900/day for a plumber and ₹650/day for a helper, and output for 25 mm CPVC work is 12 m/day. Material: 25 mm CPVC pipe ₹85/m, fittings ₹40 per fixture point, wastage 7.5%, overheads 10%, profit 15%, GST 18%. The school's engineer asks for a written quotation and mentions that a local supplier has offered an unbranded pipe at ₹55/m 'with the same look'.
1. Calculate the quantity of 25 mm CPVC pipe to be quoted, allowing for the site measurement and wastage, and state how many standard 3 m lengths to order.
Read the worked answer
Main 18 m + riser 12 m = 30 m. Branches: 22 fixture points × 4.2 m average = 92.4 m. Measured total = 122.4 m. Add 7.5% wastage = 9.18 m, giving 131.58 m. Standard 3 m lengths: 131.58 ÷ 3 = 43.86, so order 44 lengths = 132 m. Compare with the drawing's 3.0 m branch: 22 × 3.0 = 66 m; total 96 m; with wastage 103.2 m - the drawing understates the pipe by about 28 m, roughly 27%. That is why the site measurement must be recorded and approved in writing before the quotation is fixed. If the engineer insists on the drawing quantity, quote it as a provisional item with re-measurement; otherwise the plumber absorbs the extra pipe at ₹85/m plus fittings and labour.
2. Prepare a per-metre rate analysis for 25 mm CPVC pipe including labour, fittings, overheads, profit and GST. State the quoted rate rounded to the nearest rupee.
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Labour: (900 + 650) ÷ 12 m = ₹129.17/m. Fittings: 22 points × ₹40 = ₹880; over 122.4 m = ₹7.19/m. Pipe: ₹85/m. Apply 7.5% wastage to material: pipe 85 × 1.075 = ₹91.38; fittings 7.19 × 1.075 = ₹7.73. Direct cost = 91.38 + 7.73 + 129.17 = ₹228.28/m. Overhead 10% = ₹22.83, giving ₹251.11. Profit 15% = ₹37.67, giving ₹288.78. GST 18% = ₹51.98, giving ₹340.76. Quoted rate: ₹341 per metre supply-and-fix, including fittings, wastage, overhead, profit and GST. State the assumptions in the quotation - output 12 m/day, one plumber plus one helper, 22 points, 4.2 m average branch - because a change in any one changes the rate.
3. The supplier's unbranded pipe is cheaper; the school asks you to use it and to 'adjust' the quantity in the bill. How do you respond, and what should the written quotation contain?
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I would not use it. Potable-water pipe must carry the ISI mark to IS 15778 (CPVC) or the relevant standard, with a test certificate and a clear pressure/temperature rating; 'same look' says nothing about wall thickness (SDR), resin quality or joint strength. An off-grade pipe can fail the pressure test after the walls are closed, and the rework cost - breaking tiles, re-piping, re-testing - is many times the ₹30/m saved. I would also refuse to inflate the quantity: a government school bill is audited, and inflating it is fraud. The written quotation should state the scope and make/standard of pipe and fittings, sizes, measured quantities with the measurement basis, the site-approved 4.2 m branch length, unit rates, wastage, GST, payment terms, completion period, testing procedure, warranty period, and a condition that quantities are provisional and will be re-measured. The cheaper offer should be declined in writing, with the standard cited.