MUHAMMAD, S1. and MUAZU, U.

 1. Department of Building, Faculty of Environmental Design, Ahmadu Bello University, Zaria. Nigeria.


A study was conducted to estimate the quantity of water that is lost through leakages due
to faulty/malfunctioning fittings and appliances in selected sanitary accommodations,
with a view to determining its cost implication. Measuring containers and stopwatch were
used to determine the volume as well as flow rates at each point of leakage. The supply
was monitored over a period of seven days at scheduled intervals of 3 hours. Based on
this, a probable supply of nine (9) hours daily was established. The volume of leakages
was measured both for night and daytime, because of the variation in supply pressure
during the periods. Average volume of leakage in each location was established. The total
volume of leakage was estimated to be 240, 213.60 litres daily. This represents about 8%
of the total production capacity of the ABU water works, which is three million
(3,000,000) litre per day. The cost of leakage was estimated to be N 180,160.20 per
month. Bearing in mind that these figures were obtained only from selected areas, the
volume of leakage and its cost implication would be better appreciated if all locations of
leakage were considered. The problem of these leakages can be minimized by selection
of high quality fitting and appliances, and through proper maintenance of the water
supply installations.

Keywords: Water loss, Flow Rate, Leakages, Volume, Cost.


Water is one of the essential natural resources that are vital for human life. Despite the

abundance of this resource on earth, only a limited percentage is useable in terms of

meeting human needs i.e. household use (cooking, drinking, sanitation, etc), agriculture

and industrial processes. The supply of adequate and good quality water, particularly on a

large-scale is a capital-intensive venture. Huge costs are spent to construct reservoir,

complex treatment plants, and extensive distribution networks. Maintenance and running

costs of water supply system also require huge financial expenditure.

Despite effort of governments at all levels to provide portable water to various

communities, the supply situation is still far from adequate in Nigeria. Recent official

figures put access to portable water at about 60% in the country. While more efforts are

being made to improve access, there is the need also to ensure the judicious use of what is


In most water supply systems, a large percentage is lost in transit from treatment plant to

consumers (WHO 2001). Leakage may constitute a high proportion of water losses

especially if they are not discovered or controlled in good time. Besides loss of useful

quantity of water and waste of money, leakage leads to additional economic loss in the

form of damage to pipe network, erosion of pipe bedding, damage to the foundation of

roads and buildings.

Leakages are a common feature in many locations within the water distribution network

in Ahmadu Bello University. A lot of the leakages were observed over a very long period

without any action taken to control them. While the leakages may seem to be small at

each individual point, the magnitude of the problem can be quite large if all the leakage

points are considered. Unless an attempt is made to quantify the volume of water lost and

its cost implication, the effect of the leakages may not be appreciated.


The International Water Association (IWA) defines loss as the difference between the

Volume Input to the water supply system and Authorised Consumption (AWWA, 2007).

Water loss has also been defined as the difference between the amount of water produced

and the amount which is billed or consumed. There are two major dimensions of water

loss. First is the waste of useful natural resource capable of meeting the demand of

several consumers. Second is the loss of financial resource which is expended to supply

water to consumers. Water loss results in all distribution systems – only the volume

varies, depending on the characteristics of the pipe network and other local factors, the

utility’s operational practice and the level of technology and expertise applied in

controlling it (WHO 2003). According to an enquiry made in 1991 by the International

Water Supply Association, the amount of water lost is typically 20-30% of production for

the developed countries. The figure is between 25-45% for developing countries, and up

to 50% for very old systems.

Type of Water Losses

Two broad type of losses were identified by the International Water Association, i.e.

Apparent and Real Losses (AWWA, 2007). Apparent losses include unauthorized

consumption, customer metering errors and data handling errors. Real losses include

leakages on transmission and distribution mains, leakages and overflow at utility’s

storage tanks, and other form of leakages within the distribution network. The major

causes of real water losses include: Poor network design, construction and quality

control; Aging pipe network; and leakage at connections, joints, valves and fittings and

from broken mains. (WHO, 2001).

The amount of water losses will depend largely on the pressure in the system and on the

‘awareness’ time, i.e. how quickly the loss is noticed and dealt with (Stenberg, 1982).

The volume of waste also depends on the leakage detection and repair policy of the water

supply authority.

Factors influencing leakage

How much leakage is allowed to occur in a system is directly attributable to the

company’s policy, and the influencing factors can be grouped under four policy

categories (WHO 2001). These factors are:

1. Resources: financial - staffing - water.

2. Infrastructure condition: materials - renewal policy - pressure.

3. Institutional attitude: structure - regulation - politics.

4. Leakage control policy: activity - perception - technical expertise.

The availability of resources is clearly crucial to the volume of leakage. Where water is

plentiful, leakage is viewed and tolerated differently to where it is scarce. Financial

resources and manpower resources are also significant factors.

The condition of the infrastructure, and the renewal or rehabilitation policy, is perhaps

one of the main reasons for the variation in leakage across the world. The choice and

quality of materials, and their laying techniques, particularly in aggressive soils, influence

the life-span of the network. Although the age of the network itself is not always a factor,

it almost certainly becomes one when combined with the other factors. It follows that a

company’s policy for replacing or rehabilitating the pipe network is a major influence on

the condition of the infrastructure and therefore leakage.

The institutional policy largely centres on the perception of, and attitudes to, leakage.

These in turn affect the capital and staffing that are applied to controlling it. The attitude

of governments, national and local agencies, municipal authorities and the community all

influence the organization and the operation of the network. Political influences can also

be significant - serving the community by developing a new source or building a new

treatment works is more “high profile” than initiating a leak detection policy.

Finally, the leakage control policy itself determines the level of activity and the level of

leakage in a network. Policies can range from those of very low activity, like repairing

visible leaks only, to those which depend on monitoring flows into discrete zones to pick

out areas of high leakage.

Effects of leakage

The effects of leakage and waste include:

      Consumer inconvenience, by reducing pressure at taps, appliances and showers,


      Damage to infrastructure, by creating voids which can lead to collapse of

       highways and buildings;

      Excessive costs, not only from compensation payments and from repairs to

       damaged structures, but also production costs (if leakage is 50% of production,

       energy and treatment costs have been doubled);

      Increased loading on sewers due to infiltration, leading to the need to over-design

       sewer capacity;

      Introduction of air into the distribution network if the water supply is intermittent,

       causing damage to meters, and leading to over-measurement of the true

       consumption and errors in water bills;

      Health risks, in low-pressure systems or where the supply is intermittent, by

       allowing infiltration of sewage and other pollutants into the pipe network.


The study was conducted through a field survey on the main campus of Ahmadu Bello

University, Zaria. The various points and locations of leakage were identified through a

preliminary inspection of the water distribution network. Some sanitary conveniences

were selected for the study due to the large number of leakage points observed.


The materials used for the work are 250ml and 1 litre measuring cylinders, 10 litre bucket

and stop watch.


Water supply in Ahmadu Bello University experiences frequent interruptions. This made

it necessary to first establish the duration of supply in order to make a reasonable

estimate of the leakages. Scheduled visit of the locations under study was conducted at

intervals of three hours (i.e. six times in a day) for one week. Based on this, probable

supply duration of nine hours daily was established.

The measuring containers were used to quantify the volume of water that is lost through

leakages. A stopwatch was used to record the time over which a given volume of water is

lost. A total of 63 leakage points were identified in the selected locations (ICSA/Ramat

Hall, Block F2 in Suleiman Hall, Akenzua hall, Danfodio hall and the newly constructed

toilets within the academic areas).

Flow rates (in litres per second) were estimated for each leakage point. Five set of

readings were taken for each point. An average of the five readings was considered as

flow rate at that point. Because of variation in water pressure between night and day time,

flow rates were established for the respective periods. An average of the two was

considered in estimating the volume of water lost through leakages (see Table 3 in the

appendix). The estimated daily volume of leakages was obtained by multiplying the

average flow rate by the estimated daily hours of supply i.e.9 hours (see Table 1)

Data on the production capacity as well as cost of production were obtained from the

ABU water works. While the full production capacity of the water works was given as

three million litres per day (3,000,000lts/day), the current actual production capacity

could not be established. The cost of production was estimated to be N 0.020/ltr based on

personnel, maintenance and running costs of the water works. This figure does not

include fixed capital cost and hence need to be adjusted. Rates from two water works in

Zaria and Kaduna were obtained as N 0.024/ltr and N 0.030/ltr respectively (Muazu,

2005). The average of the three figures i.e. N 0.025/ltr was considered as reasonable

estimate of the cost of water supply.


Total Estimated Volume of Leakages

The total volume of leakages in each of the locations is shown in Table 1. Results show

that a total estimated volume of water lost through leakages at the locations studied was

240, 213.60 litres. This volume is about 8% of the design production capacity of the ABU

water works, which currently is not operating at full capacity due to age and some

operational problems.

Table 1. Total Flow Rates and Volume of Leakages in Various Locations

                                  Total Flow Rate for all       Estimated Daily Volume
Location                          Points of Leakage (lts/sec) Of Water Lost (lts)
Icsa/Ramat Hall                               2.368                    76,723.20
Suleiman Hall                                 1.224                    39,657.60
Akenzua Hall                                  0.808                    26,179.20
Danfodio Hall                                 1.841                    59,648.40
New Toilets within Academic Areas             1.173                    38,005.20
Total                                                     7.414               240,213.60

                                                      Source (Muazu, 2005)

Estimated Cost of Leakages

The costs of daily/monthly leakages in the various locations are shown in Table 2. This is

based on the estimated volume of leakages and estimated cost of supply of N0.025/ltr.

The estimated cost of water loss due to the leakages is N 180,160.00 monthly. If the

leakages are controlled a saving of this amount can be useful to the university in some

other areas even though being insignificant.

Table 2 Estimated Costs of Leakages

                              Daily Volume of       Daily Cost of      Monthly Cost of
Location                      Leakages (lts)        Leakages (N)       Leakages (N)
Icsa/Ramat Hall                     76,723.20            1,918.08         57,542.40
Suleiman Hall                       39,657.60             991.44          29,743.20
Akenzua Hall                        26,179.20             654.48          19,634.40
Danfodio Hall                       59,648.40            1,491.21         44,736.30
New Toilets in Academic Areas       38,005.20             950.13          28,503.90
Total                                    240,213.60           5,933.34      180,160.20
Source: Muazu (2005)

The survey also revealed that about 70% of the water leakages occur due to faulty taps

and stop valves (see Table 4). Market survey also indicated that the costs of these fittings

are between N500.00 – N 800.00. Based on the above, it is established that all the

malfunctioning fittings can be replaced at the cost of about N 40,000.00, which is less

than 25% of the estimated monthly cost of water leakages.



Inadequate water supply still remains a problem on the main campus of Ahmadu Bello

University, Zaria. While efforts are being made to improve the supply situation,

inadequate attention is paid toward minimizing the losses, particularly leakages due to

faulty fittings. Faulty taps through which water flows continuously once there is supply

contributes a very significant amount of the losses.

There is very poor response from the relevant units in terms of taking the necessary

maintenance action to stop the losses. In most of the locations studied, the leakages still

persist, unabated for over two years. The estimated volume of daily losses i.e. 240,213.60

could serve the needs of up to 2,670 persons, putting the demand at 90 litres/person/day.

Considering that this estimated volume is based on 9 hours of daily supply, higher

amount of losses would result with longer supply duration. Also, since the above figure

was obtained only from the selected areas, the overall volume of leakage and its cost

implication to the university would be better appreciated if all other areas of leakage were



The Estate Department, which is responsible for maintenance of all facilities in the

university should develop leakage detection and repair policy for the water supply

system. A sound reaction time should be given whenever leakage is identified or


Because of the large number of people using the facilities, attention should be paid to

selection of high quality fittings that would have a longer life span and reduce their

failure rate. This would possibly minimise the occurrence of leakages.


A.W.W.A. (2007) Apparent and Real Losses. American Water Works Association.


Muazu, U. (2005) An Assessment of the Cost Implication of Water Wastage in Selected
             Locations of Ahmadu Bello University Zaria. Unpublished B.Sc. Project,
             Department of Building, Ahmadu Bello University, Zaria.
Stenberg, R. (1982) Leakage Detection in Water Supply Systems. Swedish Water Works

             Association, Stockholm.

W.H.O. (2001) Leakage Management and Control-A best Practice Training Manual.

             World Health Organisation.


W.H.O. (2003) Wasted Water. World Health Organisation.



Table 3. Flow Rates for Leakage Points at Block F2 Suleiman Hall

                  Flow Rate (lts/sec) Flow Rate (lts/sec)    Average Flow
Leakage Point     At Night              For Daytime          Rate (lts/sec)
Storage Tank             0.040                 0.040               0.040
pipe joint               0.030                 0.025               0.028
WC Cistern               0.109                 0.100               0.105
WC Cistern               0.098                 0.089               0.094
Faulty Tap               0.075                 0.070               0.073
Total                             0.352                0.340              0.346

                                               Source (Muazu, 2005)

Table 4. Summary of Leakage points

Type                        Number      Percentage
Faulty Tap                     37            58.73
Missing Tap                     2             3.17
Faulty Stop Valve               6             9.52
Faulty WC Cistern Valve         7            11.11
Leaking Storage Tank            8            12.70
Leaking pipe joint              3             4.77
Total                          63           100.00

                                      Source (Muazu, 2005)


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