Drainage systems

The service connection is tapped off the municipal main with a ferrule and runs underground into the plot. A stop cock lets the supply be shut off, and the water meter records how much is used. From the meter the line runs into the sump.

The sump holds the water until it is pumped up. The pump’s suction pipe ends in a foot valve near the bottom, which keeps the pipe full of water between runs. A float switch can stop the pump when the sump runs low, and a sealed manhole cover keeps the water clean.

The pump draws water from the sump and sends it up the rising main. A non-return valve on the delivery side stops water running back when the pump stops, a gate valve isolates the pump for servicing, and a pressure gauge shows it is working properly. Pressure pumps can also boost the supply to individual floors.

The tank (shown see-through) stands on a frame above the roof. The rising main enters near the top through a float valve: the float rises with the water and closes the valve when the tank is full. An overflow pipe takes away any excess, a vent lets air in and out, and a drain at the bottom allows the tank to be cleaned.

A gate valve on the down-take just below the tank, and one on each floor’s branch, let a plumber isolate part of the system for a repair or a new fitting while the rest of the house keeps its water. Ball valves do the same job with a quarter turn.

The down-take runs down the wall from the tank outlet. At each floor a tee sends a branch along the wall to the bathroom and the kitchen; pipes get smaller as the number of outlets each one serves goes down.

Every change of direction uses an elbow, every junction a tee, and long runs are joined with couplers. Clamps fix the pipes to the wall at regular intervals so they cannot sag or vibrate. Joints are made with solvent cement or thread-seal tape and pressure-tested before the walls are closed up.

The heater takes cold water from the branch and supplies a separate hot line to the shower mixer and the basin. A safety valve protects it from excess pressure. Hot-water lines use pipes rated for hot water, such as CPVC.

The concealed mixer body is fixed in the wall before tiling and blends the hot and cold water; its diverter sends it to the overhead shower or the spout. A health faucet (hand spray) sits beside the WC, and the basin has a pillar tap.

The basin is fed through an angle valve and drains through a trap into the waste line. The WC’s cistern fills through its own angle valve; the pan connects to the soil pipe, which runs under the floor to the stack.

The sink takes a cold supply to its tap, and a separate valve feeds a wall-mounted water purifier. Below the sink a waste coupling with a strainer connects to a trap and the waste pipe, which runs out to a gully trap.

A floor trap with a grating sits at the lowest point of the bathroom floor, and the basin has its own trap. Each holds a little water that blocks sewer gases while letting waste water through. The WC’s soil pipe and the waste pipes slope down under the floor to the stack.

Soil and waste branches from each floor join the stack, which is clamped to the wall. It continues above the roof to a vent cowl so air can enter — the waste then flows freely and trap seals are not siphoned dry. At ground level a bend takes the stack into the inspection chamber.

Kitchen and floor-wash water is led into a gully trap at ground level. Its grating keeps out leaves and debris, and its water seal keeps drain smells down before the water flows on to the inspection chamber.

Inspection chambers at each junction and change of direction let the drains be inspected and cleared. From the last chamber the drain runs at a steady fall to the municipal sewer or the septic tank.

A roof outlet collects rainwater and a down-pipe takes it to the ground, where it flows into a recharge pit that lets it soak back into the ground (rainwater harvesting). It can also be led to a storage tank or the storm drain.