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Plumbing BOQ Estimator Calculator

Reference: Order-of-magnitude estimate

📋 PLUMBING

Free plumbing BOQ estimator. Order-of-magnitude bill of quantities and cost for water supply, drainage and sanitaryware from built-up area, floors, toilets per floor and units per floor.

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📐 DETAILED CALCULATIONS

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📋 ASSUMPTIONS & BASIS

Order-of-magnitude estimate

Design criteria, governing codes and assumptions.

ℹ About This Calculator

A quick plumbing budget is often needed before any detailed design. This estimator gives an order-of-magnitude bill of quantities and cost for the water supply, drainage and sanitary scope from the built-up area, number of floors, toilets per floor and units per floor, using typical per-fixture and per-square-metre allowances so you can frame a budget and compare options at concept stage.

These allowances reflect typical fit-outs but real cost depends on fixture grade, the water and drainage strategy, local rates and the detailed design. The estimate is for early budgeting and option comparison, not tender. Replace it with a measured BOQ taken off the drawings at current rates before committing.

Concept Plumbing BOQ Method

Order-of-magnitude estimate

Step 1 - Estimate fixture count from toilets and units per floor across all floors.
Step 2 - Apply a per-fixture allowance for sanitaryware, water supply and drainage connections.
Step 3 - Add per-m² allowances for mains distribution, risers and rainwater/drainage.
Step 4 - Add lump sums for pumps, tanks and the incoming/soak scope.
Step 5 - Sum into a headline value and per-fixture and per-m² benchmarks.

Worked Example

A residential block of 6 floors with 4 units per floor and 2 toilets per unit has about 48 toilets. Applying per-fixture sanitary and connection allowances plus per-m² distribution and drainage allowances and a pump/tank lump sum gives a headline plumbing budget and per-fixture benchmark.

Plumbing Budgeting Notes

Fixtures dominate

Sanitaryware and the connections that serve it usually make up the largest share of a plumbing budget, so a good fixture count is the most important input at concept stage.

Strategy drives the rest

Whether water is stored and pumped or gravity-fed, whether drainage is gravity or pumped, and how tall the building is, all change the distribution, pumps and tanks scope significantly.

From estimate to BOQ

As the design develops, replace the allowances with measured pipe, fixture and equipment quantities priced at current rates and reconcile with this early figure.

Frequently Asked Questions

What is in a plumbing BOQ? +

Sanitaryware and fittings, hot and cold water distribution, drainage and vent piping, rainwater, pumps and tanks, and the connections to fixtures — plus the incoming supply and disposal scope.

What drives plumbing cost? +

Fixture count and grade above all, then the water supply and drainage strategy (pumped vs gravity, storage, treatment) and the vertical distribution in tall buildings.

How accurate is the estimate? +

Order-of-magnitude, for concept budgeting and comparison. The reliable figure is a measured BOQ from drawings.

How is fixture count estimated? +

From toilets and units per floor multiplied across the floors. It sets the sanitaryware and connection allowances, which usually dominate the cost.

Does this replace a measured BOQ? +

No. Use it early, then measure quantities from the drawings and price at current rates.