Plumbing and drainage for new builds in Bali

Water side: fusion-welded PPR for hot and cold, sized so two showers and a kitchen tap can run at once without the temperature lurching, with isolation valves at every wet area instead of one master valve that shuts the whole house down over a tap washer. Manifolds where the layout suits them, insulation on hot runs, and every buried joint photographed against a tape before the screed goes down.

Drainage side: thick-wall PVC in the right class, soil pipe falling at around one in sixty, waste at two per cent, sweeping bends instead of tight elbows, and — the item most often missing here — real venting. A stack that cannot breathe siphons water out of the traps below it, which is why so many otherwise decent houses smell faintly of drain by their second wet season. Vents go up through the roof and stay there.

Pressure, storage and the power-cut problem

Two supply realities shape every water system on this island. Mains pressure, where PDAM reaches at all, is unreliable and often arrives at night; and power cuts stop pumps, which stops water. So the standard answer is storage plus pressurisation: a ground tank holding at least a day of use, a pump matched to fixture demand, and a pressure vessel so the pump is not cycling every time somebody washes their hands.

Sizing is arithmetic rather than opinion. A four-bedroom house with a kitchen, staff bathroom and garden taps rarely needs more than a one-horsepower booster, but it does need the right tank — undersized storage is why guests find a dead shower at seven in the morning. Where the supply is a well, the submersible and the booster are two different pumps doing two different jobs, and combining them is the most common false economy we are asked to unpick.

Getting the falls and the vents right

Gravity drainage has almost no tolerance for optimism. Too flat and solids strand; too steep and the water runs away from them with the same result. We set soil pipes at roughly one in sixty and waste at two per cent, then check every run with a level rather than an eye, because a ceiling void hides a sagging pipe until the day it stops hiding it.

Venting is the other half, and it is what quietly gets deleted from budget builds. Every trap needs air behind it, or the next discharge pulls its seal out and leaves the septic tank breathing into your bathroom. We run vent stacks above roof level, use anti-siphon valves only where a stack genuinely cannot reach the roof, and fit cleanouts at every change of direction — because in twenty years somebody will need to rod that line, and they should not have to demolish a wall to do it.