Bathroom Site Measurement Checklist (India): The Survey to Do Before You Design

A designer with a laser measure and clipboard recording dimensions and existing plumbing positions in a bare Indian bathroom before renovation, with pipe stub-outs and a floor drain visible

Almost every bathroom that goes wrong on site went wrong at the survey. A drain that sits 40 mm higher than assumed, a beam that eats the shower head clearance, a shaft you cannot actually reach, a floor level that steps down into the bedroom — these are not construction failures, they are measurement failures, discovered too late. This document is the fix: a structured site-measurement and survey checklist you fill in on the first proper site visit, before a single line of the design is drawn.

It sits right at the front of the project — after the brief, before the layout. Whoever surveys (the designer, the site engineer, or a senior contractor) walks the space once with a laser measure, a torch, a pressure gauge and this sheet, and leaves with a complete as-built record. Copy the tables below into your project file or a tablet form and adapt the rows; the goal is that nobody ever has to say "I think it was about…".

Two readings decide whether a bathroom drains and finishes correctly: the finished-floor-level (FFL) datum and the existing drain invert. Establish a single datum on day one and tie every level to it. Everything else is arithmetic.

How to use this document

When: on the first site visit, once the space is accessible (ideally after any loose fittings or a demolished old bathroom are cleared, so you read the real slab and stub-outs).
Who: the designer or site engineer surveys; a contractor or plumber should be present to open shafts, confirm pipe routes and help run the pressure check.
What you carry: laser distance meter (plus a steel tape for cross-checks), a spirit level or laser level, a torch, a pressure gauge that screws onto a tap, a moisture meter if renovating, a phone/camera, and this sheet.
How you record: measure every dimension twice, record in mm (not "feet-ish"), photograph every item as you note it, and mark one datum line on a wall in marker or tape so every level references the same zero.
Output: a filled sheet plus a numbered photo set becomes the basis of your layout, your services drawing and your BOQ. Nothing in the design should rely on a number that is not on this sheet.

1. The measurement record

The core of the survey. Record everything that will constrain the layout and the levels. Every dimension in mm; every level referenced to your single FFL datum. The example rows are indicative of a typical mid-size Indian bathroom — replace them with your actual readings.

Item	What to record	Unit	Example
Room envelope	Internal length × width, at floor and at 1.5 m height (walls are rarely square)	mm	2400 × 1800 (floor); 2385 × 1795 (high)
Clear ceiling height	Slab soffit to structural floor, at several points	mm	2900
Beam drops	Depth and position of every down-stand beam / lowered slab band	mm	300 deep beam, 600 from door wall
Door opening	Structural width, height, wall thickness, swing direction, sill level	mm	750 × 2100, opens out, sill +0
Window / ventilator	Width, height, sill height above FFL, which wall, opens to (shaft/external)	mm	600 × 450, sill +1500, to shaft
Existing FFL vs corridor	Step up/down between bathroom finished floor and adjoining room floor	mm	−25 (bathroom 25 below bedroom)
FFL datum line	Mark one datum on a wall; record its height above structural slab	mm	datum +1000 above slab
Existing WC drain	Centre of soil outlet from finished walls (X and Y), plus invert level below datum	mm	300 from rear, 450 from side; invert −180
Floor trap / drain	Position of each floor gully / nahani trap and its invert level	mm	trap at 600/600; invert −210
Existing water supply	Position and height of hot & cold stub-outs at each fixture	mm	basin stubs +550, 100 apart
Waste points	Basin / shower waste positions and invert relative to datum	mm	basin waste −120; shower −160
Electrical points	Existing switch, light, geyser, exhaust and shaver points — position + height	mm	geyser point +1800, rear wall
Water pressure	Static and running pressure at the highest tap, morning peak	bar	0.8 static / 0.5 running

Why the two levels matter. The FFL datum is your single zero; mark it, and every fixture height, tile course and threshold is measured from it, so nobody argues about "which floor". The drain invert — the inside-bottom of the existing soil/waste pipe below that datum — dictates whether the new WC and floor gully can fall to the stack by gravity. If the new floor build-up plus the required fall does not clear the existing invert, you must raise the floor, re-route, or add a pump — and you want to know that now, not after tiling.

2. Services and constraints survey

The room fits. The question this table answers is whether the services can be delivered and whether the structure lets you touch what you need to. Walk it with the plumber and open things up.

Constraint	Check / record	Typical India note
Shaft access	Can the plumbing shaft be reached from this bathroom? Access panel present? Size?	Apartment cores often share a shaft; confirm you can reach the stack
Soil stack & vent	Diameter and position of the main soil stack; is it vented above roof?	110 mm UPVC/PVC typical; note if branch or main
Hot-water source	Instant geyser / storage geyser / solar / central hot water? Location and pipe size?	Storage geyser 15–25 L is common; note CPVC hot line run
Ventilation	Openable window, shaft, or mechanical exhaust only? Existing duct route?	Internal bathrooms need mechanical exhaust to outside air
Slab thickness	RCC slab depth and whether a sunk/dropped slab exists for plumbing	Traditional Indian bathrooms use a sunk slab; confirm sunk depth
Structural walls	Which walls are RCC/shear or load-bearing vs infill blockwork?	You cannot chase or move structural walls — mark them clearly
Chase feasibility	Depth of chasing allowed in each wall for concealed pipes	Concrete/shear walls: surface route or box in, do not chase deep
Waterproofing state	Existing membrane condition; signs of past leaks; moisture-meter reading	Note damp on ceiling below — an existing leak to solve first
Drainage fall available	Vertical room between drain invert and stack connection for the fall	Need continuous fall to the stack; measure it, don't assume
Water shut-off	Location of the isolation valve serving this bathroom	Confirm you can isolate without shutting the whole flat

3. Photo and documentation checklist

Numbers without photos are half a survey. Shoot in order, keep them numbered against the sheet, and always include a tape or a scale object in shots of stub-outs and drains.

Photo / document	Capture	Purpose
Each wall, straight on	All four walls full-height	Reconstruct the room and spot obstructions
Corners & ceiling	All corners; ceiling with any beam drops	Check square, capture beams and slab bands
Every stub-out	Water supply points with a tape held to them	Confirm heights and spacing for the drawing
WC outlet & floor trap	Close-up with scale, plus the datum mark in frame	Record invert positions unambiguously
Shaft / access panel	Open shaft interior; stack and branches	Prove access and route before you promise it
Geyser & electrical points	Existing points and DB position	Plan the electrical layout and load
Existing leaks / damp	Any staining on ceiling below or walls	Evidence for scope and for the client record
Datum reference	The marked datum line with a level against it	Anchor every later measurement
The filled sheet	Photograph the completed handwritten sheet	Backup before it is typed up

Common mistakes

No single datum. Everyone measures from a different "floor" and the levels never reconcile. Set one datum first; reference all levels to it.
Assuming the drain invert. Guessing the fall is how a WC ends up not clearing the stack. Measure the invert; if you cannot see it, dig or open up before you commit.
Reading the room once, at floor level. Walls lean and taper. Measure at floor and at 1.5 m, and record both.
Ignoring beams and sunk-slab depth. The beam that steals your shower clearance and the sunk depth that dictates your build-up are the two most-missed readings.
Skipping the pressure check. A layout with a rain shower on 0.4 bar disappoints on day one. Test at peak, not at midnight.
Not confirming shaft access. Promising a concealed run to a stack you cannot actually reach forces an ugly surface route later.
Treating this as final. These are indicative example rows and a starting template. Verify every reading against the actual site, the contract scope, and local codes or a licensed professional before you design or price.

Related resources & guides

Bathroom design checklist (India) — the master checklist this survey feeds into.
Small bathroom design (India) — where accurate millimetres matter most.
Bathroom layout guide (India) — turning these measurements into zones and clearances.
Bathroom renovation checklist (India) — the wider renovation sequence around the survey.