Direct answer: Bathroom leak repair cost depends on the cause. Grout gaps and drain joint leaks are small local repairs. A leaking concealed pipe means opening tiles at the leak; full concealed plumbing replacement starts around Rs 28,000. Failed floor waterproofing needs a floor redo at Rs 35 to Rs 85 per sq ft plus new tiles.
A damp patch on your downstairs neighbour's ceiling is stressful for everyone. The first instinct is to call someone to "do waterproofing", but waterproofing is only one of five common causes, and it is the most expensive one to fix. Paying for a full floor redo when the real problem is a cracked pipe joint wastes money and does not stop the leak. This guide explains how to find the cause, what each repair involves, and what it typically costs in Bengaluru.
Rates below come from our bathroom renovation cost guide for Bangalore and are before 18 percent GST. Where a repair is too site specific for a fair number, we list the factors that decide the price instead.
First, find out where the water comes from
The pattern of the damp patch below tells you a lot before any tile is broken.
- Damp all the time, even when nobody uses the bathroom: points to a pressurised supply pipe, because those pipes always hold water.
- Damp only after showers or floor washing: points to grout gaps, the floor trap (nahani trap) joint, or failed floor waterproofing.
- Damp after flushing: points to the WC outlet joint or the soil pipe connection.
- Damp near an outer wall after rain: may be external wall seepage, not the bathroom at all. In Bengaluru this shows up mostly during the June to October monsoon.
Simple tests help confirm it. Close the bathroom inlet valve and watch the water meter or tank level; if it still drops, a supply line is leaking. A ponding test (closing the drain and holding water on the floor for some hours) shows whether the floor itself lets water through. Some plumbers also use a pressure test on the supply lines or a moisture meter on the ceiling below.
Repair cost by cause
| Cause | What the repair involves | Typical cost basis (before GST) | What pushes it up or down |
|---|---|---|---|
| Grout and tile joint gaps | Raking out old grout, cleaning, regrouting the wet area | Small job priced by area and grout type; no fixed band, ask for a per sq ft rate | Epoxy vs cement grout, wall height covered, condition of tiles |
| Floor trap or drain joint | Opening tiles around the drain, resealing or replacing the trap, local waterproofing, retiling the patch | Local waterproofing Rs 35 to Rs 85 per sq ft of treated area; tiles Rs 60 to Rs 150 per sq ft plus Rs 100 to Rs 150 per sq ft laying for the patch | Matching old tiles, depth of the sunken slab, trap type |
| Concealed supply pipe leak | Locating the leak, cutting tiles at that point, replacing the pipe section, retiling | Spot repair priced per point; full concealed plumbing replacement starts around Rs 28,000 per bathroom | Old GI pipes elsewhere in the wall, number of leak points, tile matching |
| WC outlet or soil pipe joint | Removing the WC, resealing or replacing the outlet connector, refixing | Usually a small plumbing job; price depends on access | Wall-hung vs floor-mounted WC, condition of the soil pipe |
| Failed floor waterproofing | Removing floor tiles, cleaning the base, new two-coat waterproofing, ponding test, new tiles | Waterproofing Rs 35 to Rs 85 per sq ft (about Rs 15,000 to Rs 30,000 for a 45 sq ft bathroom) plus new tiles and laying | Bathroom size, whether walls are redone too, membrane vs cementitious system |
If the floor waterproofing has failed and the walls, fittings and plumbing are also old, it is often better value to do a full renovation once. A full renovation of a standard 40 to 45 sq ft bathroom costs Rs 1.2 lakh to Rs 3 lakh for a mid-range finish, and a basic Essential tier job can close near Rs 90,000.
Why the cheapest fix can cost more
- Chemical injection or surface coatings over tiles can slow a leak for a while, but they do not repair a broken pipe or a failed membrane under the tiles. If the patch returns after the next monsoon, the money is lost.
- Retiling without new waterproofing hides the problem but does not stop water reaching the slab.
- Skipping the ponding test after new waterproofing means a defect is found only after tiles are laid, when fixing it means breaking them again.
Bengaluru specifics: apartments, associations and timing
- Tell the association early. Most Bengaluru apartment associations have a process for leak complaints, and many need an interior or repair work request before work starts. Vertical drain and soil stacks are often common pipes, while lines inside your bathroom are usually yours. Who pays for what depends on your association by-laws, so check them before work begins.
- Coordinate with the flat below. The repair is often checked from their ceiling during testing. Agree a time for inspection and for repainting their ceiling once the leak stops.
- Monsoon timing. Waterproofing needs a dry base and curing time. Work in the June to October rains takes longer and needs extra care. If the leak is active, do not wait for the dry season; fix the source first.
- Hard borewell water. Scale from hard water damages fittings and diverters over time, which can cause drips inside the wall. Check concealed diverters and stop valves when you repair.
- Approvals. Internal bathroom repairs in a flat usually need only the association's permission, not a GBA approval. Structural or external drainage changes are different.
Leak repair checklist
- Note when the damp patch below gets worse: always, after showers, or after flushing.
- Close the bathroom inlet valve and check the meter or tank level.
- Ask for a diagnosis before a quote, and ask the contractor to name the cause in writing.
- Check whether the leak is in your lines or in a common stack.
- Get the association's work permission and timings.
- If waterproofing is redone, insist on two coats and a ponding test before tiling.
- Ask what is guaranteed and for how long, in writing.
- Agree who repaints the ceiling below once it dries.
Frequently asked questions
Can a bathroom leak be fixed without breaking tiles?
Sometimes. Grout gaps and some WC outlet leaks can be fixed without breaking tiles. A leaking concealed pipe or failed floor waterproofing needs tiles to be opened at least locally.
Who pays when my bathroom leaks into the flat below?
Generally the owner of the bathroom where the leak starts pays for the repair, unless the source is a common pipe maintained by the association. The exact rule depends on your association by-laws and any agreement between the two owners.
How long does a bathroom leak repair take?
A grout or joint repair can take a day or two. A floor waterproofing redo with a ponding test and retiling takes longer, and a full bathroom renovation typically takes 12 to 20 working days.
How do I know if waterproofing has failed?
If the patch below appears after the floor is wet, grout is intact, and supply pipes hold pressure, failed waterproofing is likely. A ponding test confirms it.
Will the stain on the ceiling below go away?
Once the source is fixed and the slab dries, the ceiling below can be scraped and repainted. Painting before it dries usually brings the stain back.
How myNivasa can help
myNivasa has delivered 100+ projects in Bengaluru since 2018. For a leak, we start with the cause, not with a waterproofing quote, and we include a ponding test whenever waterproofing is redone. See our home and bathroom renovation services, read about terrace waterproofing cost if you live on a top floor, or book a free site visit: call +91 94499 00222 or email [email protected].
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