Bad plumbing is invisible until it's a disaster. A leaking pipe inside a wall, a drain that won't clear, a bathroom that smells — all of these trace back to mistakes made during construction, not after.
Here's what to watch out for and how to get it right the first time.
Mistake 1: Using the Wrong Pipe for the Job
Not all pipes are the same. Using the wrong type in the wrong place is one of the most common — and costly — mistakes.
- CPVC pipes — for hot and cold water supply inside the home. Can handle high temperatures and pressure.
- PVC pipes — for cold water supply and drainage only. Never use for hot water — it warps.
- UPVC pipes — for drainage, sewage, and outdoor use. Strong and chemical resistant.
The rule is simple: hot water lines need CPVC. Drainage needs UPVC. Never mix them up.
Mistake 2: No Slope in Drainage Pipes
Drainage pipes need gravity to work. Water doesn't flow uphill.
Every horizontal drainage pipe must have a minimum slope of 1:40 — meaning 1cm drop for every 40cm of pipe length. If the slope is wrong or missing, water sits in the pipe, waste accumulates, and you get constant blockages and bad smells.
This needs to be checked and verified before pipes are covered. Once the floor is laid, there's no fixing it without breaking everything open.
Mistake 3: Missing P-Traps and Water Seals
A P-trap is the U-shaped bend under every washbasin, sink, and floor drain. It holds a small amount of water that blocks sewer gas from coming up into your home.
Many contractors skip or incorrectly install P-traps to save time. The result — your bathroom smells like a sewer, especially in rooms that aren't used daily.
Every drain point — washbasin, kitchen sink, bathroom floor drain, balcony drain — must have a proper P-trap.
Mistake 4: Pipes Too Close to Electrical Lines
Water and electricity don't mix. Plumbing pipes and electrical conduits should never run parallel and close to each other inside walls.
Minimum clearance of 150mm should be maintained between water pipes and electrical conduits. This is a basic safety requirement that gets ignored on busy sites.
Mistake 5: No Isolation Valves
An isolation valve lets you shut off water to one section — one bathroom, one floor, one appliance — without cutting supply to the whole house.
Many homes are built with only one main stopcock at the inlet. So when a tap washer fails or a geyser needs replacing, the entire house water supply has to be turned off.
The right approach:
- One isolation valve per bathroom
- One isolation valve per geyser
- One isolation valve per kitchen
- One main stopcock at the inlet
These are cheap to add during construction and invaluable later.
Mistake 6: Joints Inside Walls
Pipe joints are the weakest point in any plumbing system. Putting joints inside walls or under floors — where they can't be accessed — is a serious mistake.
If a joint leaks inside a wall, you won't know until there's a damp patch or the wall paint starts bubbling. By then, the damage is already done.
Best practice: run full-length pipes inside walls wherever possible. Keep all joints at accessible locations — inside cabinets, at visible junction points, or in accessible service areas.
Mistake 7: Geyser Point Too Close to the Outlet
The geyser should be installed as close as possible to where hot water is used. Every extra meter of pipe means more hot water sitting in the pipe that cools down before it reaches you — wasting water and time every morning.
Plan your geyser position during construction, not after. Ideally:
- One geyser per bathroom, mounted close to the shower/tap
- Avoid a single centralised geyser for the whole house — the heat loss over long pipes is significant
Brands to Insist On
- Ashirvad — most trusted brand for CPVC and UPVC in South India
- Astral — excellent quality, wide availability
- Supreme — reliable for both CPVC and PVC
- Finolex — good value, widely available
- Jaquar / Cera / Hindware — for taps, fittings and sanitary ware
Avoid unknown or unbranded pipes and fittings. The price difference is small. The replacement cost when they fail inside a wall is not.
Before Floors and Walls Are Closed — Checklist
- ✅ All pipes tested with water pressure before closing walls
- ✅ Drainage slope verified at every horizontal run
- ✅ P-traps installed at every drain point
- ✅ Isolation valves in place for each bathroom and geyser
- ✅ No pipe joints hidden inside walls or under floors
- ✅ Hot water pipes (CPVC) separate from drainage pipes (UPVC)
- ✅ Minimum 150mm clearance from electrical conduits
Need help buying branded plumbing materials? ABBAGA works with trusted brands across Bangalore, Mangalore, Udupi, Kundapura and Coastal Karnataka.