Building Services: Taps & Water Supply – JSS2 Basic Technology Lesson Note (Third Term)

A tap is a valve that controls the release of a liquid or gas, and plumbing is the system of pipes and fittings that supplies water to a building and drains liquid waste out of it.

Behavioural objectives

By the end of the lesson, students should be able to:

1. define a tap and plumbing;
2. name the types and styles of taps and say how taps work;
3. state the uses of the main fittings in a domestic pipeline;
4. explain why a water storage tank is needed;
5. describe how sinks, basins, bathtubs, showers, water closets and hot water systems are provided in a building;
6. describe the drainage system and the practices that keep a septic tank working.

What is a tap?

A tap is a valve that controls the release of a liquid or gas.

• Materials: taps are made from stainless steel, chrome, brass, nickel and even gold.
• Position: a tap is fixed at the end of a supply line, where water is drawn off.
• Use: opening the tap lets water flow out, and closing it stops the flow.

What are the types of taps?

There are three main types of washerless tap: ball, cartridge and ceramic disc.

• Ball tap: a hollow plastic or stainless steel ball is pushed over a rounded cover, which controls the temperature and flow of water.
• Cartridge tap: a lever controls a plastic or brass cartridge, which moves up and down to restrict flow and from left to right to change temperature.
• Ceramic disc tap: two ceramic plates slide over each other to regulate temperature and flow. It needs the least maintenance of all types.

What are the styles of taps?

There are two common styles of tap: the cross head tap and the lever tap.

• Cross head tap: has a four-armed handle that is turned round to open or close the tap.
• Lever tap: has a lever handle that is lifted, pushed or turned a short way to open the tap.

How do taps work?

Different taps regulate water in different ways, and the compression tap is the most familiar.

1. The handle is turned to screw the spindle down.
2. The spindle presses a washer made of rubber or neoprene against a metal seat.
3. The washer blocks the opening, so water flow is restricted or stopped.
4. Turning the handle the other way lifts the washer and water flows again.

• Maintenance: washers wear out over time and must be replaced.

What is plumbing?

Plumbing is the system of arranging and connecting pipes with fittings and machines to supply water to a building and drain liquid waste out of it.

What are the components of a domestic pipeline fitting?

The main fittings in a domestic pipeline are the stop cock, drain cock, valves, taps, elbows and tees.

• Stop cock: controls the flow of water through supply pipes. Its crutch handle is turned clockwise or anticlockwise to raise or lower the jumper on the valve seating.
• Drain cock: is connected to a water supply pipe so that water can be drained off.
• Gate valve: controls the flow of water in the distribution pipes.
• Ball valve: a float-operated valve that shuts off water entering a tank or cistern when it is full.
• Tap: gives a supply of water when opened at the end of the supply line.
• Elbow: changes the direction of flow through an angle, for example joining a horizontal pipe to a vertical pipe. Common angles are 90°, 112½°, 135° and 157½°.
• Tee: joins three pipes meeting at a junction. Flow from one pipe divides into the other two.

How is water supplied to a building?

Water reaches a building from underground street mains, passes the stop cock and is shared between the taps and an overhead storage tank.

1. Pipes called the mains are laid underground to carry water to various outlets.
2. Water from the street mains enters the compound in a 30 mm diameter pipe (the community pipe).
3. The pipe connects to one side of the water authority stop cock, which is buried in a pit at least 80 cm deep.
4. The main is connected to the kitchen sink, to the outside tap and up to the elevated tank.
5. The bath, water closet, wash-hand basin and hot water system are supplied by gravity from the overhead tank through a 22 mm diameter pipe.

Why is a water storage tank needed?

A water storage tank is needed because a regular supply of water cannot be guaranteed.

• Changing demand: demand varies during the day, from a peak in the morning to a low in the evening, and the tank evens this out.
• Low pressure: water leaves the tank at low pressure, so a leak on this line is less serious than a leak on the high-pressure mains.
• Supply cuts: the water authority sometimes cuts off supply to carry out repairs, and without a tank the building has no water.

What fittings are used for washing and waste disposal?

The main fittings are sinks, basins, bathtubs and showers, water closets and the hot water system.

What is a sink?

A sink is a fixed container, usually in the kitchen, used for washing dishes and other items.

• Material: stainless steel or enamelled steel.
• Taps: pillar or bib taps, depending on the orientation of the water supply pipe.
• Overflow hole: gives water a passage out if the tap is carelessly left open.
• Stopper: blocks the waste outlet so that a pool of water is available for washing.

To clear a blocked sink, follow these steps:

1. Place a sink plunger (force cup) over the waste outlet.
2. Plunge forcibly as many times as necessary. The compressive force moves the obstruction out of the way.
3. If this fails, unscrew the clearing eye.
4. Push a wire into the piping to dislodge the offending material.

What is a wash basin?

A wash basin is a small fixed bowl used for washing hands and face.

• Material: usually ceramic.
• Components: almost the same as those of a sink.

What are bathtubs and showers?

A bathtub is a large fixed container for bathing, while a shower sprays water over the body.

• Bathtub sizes: baths come in different sizes and shapes.
• Bathtub material: enamelled cast iron or acrylic plastic.
• Bathtub fittings: cold and hot water taps, and a stopper to hold or release water.
• Shower advantage 1: it uses water more economically than a bathtub.
• Shower advantage 2: it is more hygienic.

What is a water closet?

A water closet (W.C.) is a toilet fitting that uses flushing water to carry human waste into the drain.

• Importance: it is one of the most important parts of a household’s plumbing.
• Fault risk: any malfunction leads to an unhealthy environment.
• Cistern: holds at least two gallons of water for flushing.

What is a hot water system?

A hot water system supplies warm water for bathing and for brushing the teeth at the wash basin.

• Source of heat: an electric water heating system.
• Delivery: hot water is piped to the bathtub and wash basin.

How do the washing fittings compare?

How does the drainage system work?

A drainage system is the set of pipes that carries liquid waste from the kitchen sink, bathtub, wash-hand basins and water closets out of a building.

1. Effluent flushed from the W.C. travels through the soil pipe into the inspection chamber, the junction for all drains.
2. Water from the wash basins travels through a separate pipe into a gulley, where solids are removed.
3. The drain from the gulley then enters the inspection chamber.
4. From the inspection chamber, the liquid waste goes into the public sewage works or into a septic tank.

What is a septic tank?

A septic tank is an underground chamber that receives sewage from the house and releases clean effluent.

• Inlet and outlet: the inlet is slightly higher than the outlet.
• Displacement: fresh sewage entering the tank pushes an equal volume of old liquid into the filter tank.
• Anaerobic bacteria: these live without free oxygen and break the solids into liquid, gas and mineral sludge.
• Aerobic bacteria: these live in oxygen and finish purifying the effluent by oxidation in the filter tank (second chamber).

What practices keep a septic tank working?

A septic tank works well when the bacteria in it are not killed and the tank is not overloaded.

• Avoid disinfectants: they kill disease germs in the toilet but also kill bacteria in the tank, which slows the breakdown of waste.
• Limit household chemicals: too much bleach or detergent interferes with bacterial action and reduces the soil’s rate of absorption. Effluent may then rise to the surface and pollute the area.
• Avoid sudden large volumes of water: they churn up solids and sludge still being broken down. These can flow into the filter or drainage field and clog it.
• Test the soil first: find out the absorption properties of the soil before installing a septic tank.

Evaluation

1. Define (a) tap (b) plumbing (c) sink (d) basin.
2. State three types of tap.
3. Explain five domestic pipeline fittings and state their uses.
4. Explain the following: (a) sink (b) water closet (c) storage tank.
5. Mention three practices to be noted in the use of septic tanks in our homes.

Assignment

Write short notes on the following: (a) the uses of a stop cock, a drain cock and a tee; (b) two reasons why a water storage tank is needed; (c) two advantages of installing a shower.