The problems normally faced in  water supply distribution system are:

1. Un-accounted for water (Leakage and Wastage of water),
2. Degradation of quality of water,
3. Reduction in carrying capacity, and
4. Inadequate pressures at tail ends of the system

• Un-Accounted For Water

Un-accounted for water (UFW) is the quantity of water, which is not actually billed for and water charges for the same are not realized from the consumers.

The UFW water can be of two types:

1. Physical loss and
2. Nonphysical loss.

• Physical loss

Physical loss is the water actually lost through leakage and wastage. Leakage is the water lost from storage reservoir, transmission main, service reservoirs, and distribution system and house service connections through leaks from cracks, holes or joints of pipe lines and due to corroded pipes, and fittings in house service connections. Wastage is the operational loss and the wasteful use and misuse of water by the consumers.

Wastage of water can also occur due to discarding of stored water when fresh water supply comes in the case of intermittent water supply system.

Operational loss is the water used in the system for cleaning of filter beds by back washing, sludge removal from clarifiers, periodic cleaning of the service reservoirs, periodic flushing of the deposits in the transmission mains and distribution pipes and water lost during attending bursts, leaks and other repair works.

• Nonphysical loss

Nonphysical loss is the quantity of water lost due to

1. the mechanical errors in meters at the source, at various points in the water supply system and at the consumers’ connections, which are recording lesser quantity of water than the actual quantity of flow.
2. Human errors in reading or recording the meter reading lesser than the actual quantity, and  Flow through illegal connections, which are not accounted and billed for Nonphysical loss of water is considered as the loss of revenue.

• Causes for Leakage

The causes for the leakage in the pipeline could be attributed to various factors as shown in

The causes for the leakage in pipeline are due to the following aspects also.

1. The use of sub-standard pipes and fittings leads to imperfect jointing, causing leakage in joints.
2. Selection of pipe material with out considering the corrosives of the soil in which the pipes are to be laid and the quality of water the pipe has to carry, which eventually may lead to corrosion of the pipes and fittings.
3. Lack of quality control in jointing of pipes while installation, which may result in leaks in joints when there is settlement of the supporting soil.
4. Non-conducting or improper conducting of hydraulic pressure testing of pipeline and joints at the time of installation.
5. Soil movement particularly when the pipes are laid in swelling soils like clay, due to change of moisture content, which may cause disturbance to the pipes and joints ultimately resulting in leakage.
6. Water hammer pressure disturbs the joints resulting in leakage.
7. Not detecting and rectifying the badly leaking joints regularly. Even in a properly maintained system, at any time 10% of the joints will be seeping joints (with the loss of water of 1 to 3 Lph / joint) and 1% of the total joints will be badly leaking joints (with the loss of water of 90 to 200 Lph / joint).