Expert Advice

Need a permanent Waterproofing Solution?

December 8, 2017 — by Navneet Malhotra


“I really don’t know, what would hurt more; a small yet ugly patch of dampness that is embarrassingly visible in your manicured living room or a reasonably camouflaged damp wall that is now starting to grow mold??”

Be it a bungalow or an apartment, dampness has plagued homes in every income group and in every corner of the globe.

Often a cause for depression, water seepage is quite like a divorce in marriage. The ugly signs of both appear either right away or else, after a couple of decades. An early appearance of a problem in case of water seepage, is almost entirely due to poor workmanship or inadequate protection employed by the home owner. In spite of onsite checks, just a small fraction of all plumbing related leakages could be blamed on material failure. With such high dependence on the skills of the person executing the job, it becomes imperative for us to select our plumbing contractor/waterproofing applicator through recommendation only.


Even if the plumber is currently engaged in many jobs in the condominium or society or is referred through your local sanitary and hardware shop, don’t hesitate to get his reviews from earlier customers. It is far better to wait for a skilled person than to waste your time and energy on a ‘Quack’. Search for agencies that specialize in plumbing contracts or water-proofing, as the case may be. They are often slightly expensive but they are worth their weight in mold.


Often in prolonged conditions of dampness, a white powdery substance appears on the surface… these are called ‘molds’ and they indicate the starting of rapid deterioration of the existing surface finish. Like yeast or mushrooms, molds are a part of fungi family, which are neither animal nor plants but are recognised as a kingdom of their own. Black or White in colour, they multiply rapidly in hot and moist conditions…devouring almost any organic substance. They reproduce and colonize through microscopic ‘spores’ that travel through air, surviving a long duration of harsh environments. They can lead to multiple respiratory ailments and can be especially troublesome for asthmatic patients. They can play havoc in closed ‘air conditioned’ spaces.



Water has the uncanny ability to permeate through brick and concrete to show up with ease, on the other side as dampness. There are two main sources of dampness in buildings:

1. Dampness due to leaking pipes and

2. Moisture absorbed through the surface of the structure: i.e. external walls, terraces and balconies.

Let us look at each of these categories and figure out some simple “How to” preventive solutions.

Dampness due to leaking pipes or faulty plumbing:

Water leakages through faulty pipe joints buried in floor or walls are the most painful and time-consuming to repair. Often the cause for disputes among neighbours, this dampness at times outlives the entire life of the building. Though the actual cost of pipe repair itself is extremely small yet the cost of redoing the entire wall tiles, fittings and fixtures, alongwith the loss of being able to use one bathroom during the process of repair that dissuades most users from taking immediate action. Had these pipes not been buried in the wall and floors we would have been able to repair every leak in hours…just like in the hotel industry. Yet for aesthetic reasons and our desire to alter the internal layout of the bathroom, builders end up burying water supply pipes in the walls and the disposal pipes in the floor.

While it is still simpler to detect leakages in water supply pipes, repairing either one of them is another story.

How to detect the source of leak?

1. In water supply pipes: (from the ‘overhead water tank’ to the ‘bathroom’)

‘Water supply pipes’ have a much smaller cross-sectional size than water discharge pipes. The continuous presence of water also induces constant pressure in these pipes. It is easy to isolate the hot and cold-water circuit by simply plugging the source at the terrace level. You could now connect an inexpensive and readily available hand pump fixed in a bucket with a pressure gauge, to this isolated water pipe circuit, through any one of the taps in the bathroom. We now increase the water pressure inside the closed loop of pipes by inducing extra water through our hand pump. This increase in water pressure quickly shows up on the pressure gauge installed on the pump.


Typically we induce about one and a half times the designed pressure of the pipes or 10 PSI and hold it there for a few hours. Drop in pressure would quickly identify the circuit that has the leak. Simple…right? This test is good for new pipes only as old rusted G.I. (Galvanized Iron) pipes would burst under increased pressure.

2. In water discharge pipes: Leakage in the water discharge pipes below the floors are far more difficult to detect as water tends to travel some distance before appearing on the other side of the wall/slab. It is rather difficult to pinpoint the source of dampness from either the ‘W.C’ (soil pipe) or from the floor trap1 adjacent to the ‘W.C’ that is connected to the ‘waste pipe system’. With limited success, we have been able to locate the source of leak in some cases…by discharging large quantities of different colour water in separate outlets within the bathroom. For example: by discharging blue colour ink mixed in water for ‘W.C.’ and potassium permanganate (red colour) for the floor trap next to the ‘W.C.’ and so on…and hope to see the signature colour on the other side before attempting to repair the same. The best way till date is to take advise from people with experience in the trade.

Floor trap is that part of the water discharge pipe (under the floor) that has a small bowl with water to prevent foul smell to enter the bathroom from outside.

How do we get the waterproofing in a bathroom right?


Be it a new construction or renovation of an old problematic bathroom…getting the water proofing system right is crucial to achieving a problem – free end result. Though I could share many methods, they eventually depend on four golden rules:

1. Golden Rule no.1

Employ the best plumber you can get. Without faulty joints and leaking pipes you wouldn’t even need waterproofing…. but then, even the best guys make mistakes, so just in case… get the waterproofing done!

2. Golden Rule no.2

Get a specialist-waterproofing agency to advice and execute the job. In spite of all the varied options and systems available in the market, a good waterproofing agency would save you sleepless nights. A reputed firm would guarantee against water leakage for 10 to 25 yrs. (depending on the situation and the system employed).

3. Golden rule no.3

Buy high quality (reputed) pipes only. A quick survey would introduce you to the market leaders. Remember, all ‘I.S.I’ brands are not good.

I personally prefer the use of non-corrosive Heavy duty (6kg/rm-weight) P.V.C. pipes for water discharge [both Supreme and Prince makes are good] and Copper pipes for water supply…if not, then a ‘class-B’ G.I. (galvanized iron) pipes [from Jindal]. Always pressure test and moisture protect the pipes with ‘Black tar paint’, and then polythene wrap before inserting them in wall/plaster.


4. Golden rule no.4

Always try and leave access for maintenance. A small ‘door bend’ here or a ‘clean-out-plug’ there, with a window to access the pipes, goes a long way. I am sure your designer would understand and appreciate, if you mention it to him.

All though the above rules may end up costing you in excess of 40% of the total piping and waterproofing cost but it is still a small fraction of the total investment in the bathroom and a miniscule price to pay as insurance policy against leakage.

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Navneet Malhotra

Navneet Malhotra

Navneet Malhotra is a perpetual student. His passion to design and his deep rooted desire to demystify Indian construction system has seen him as a visiting faculty member with S.P.A.-Delhi for over 8 yrs. He has also authored several ‘How-to’ articles as well as regular 'Q&A' section for ‘Better Interiors’ magazine,. B-Arch [S.P.A.-D], M-Tech [I.I.T.-D]


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