A-Z of Best Practice in Water Installations

Water use Audit of CSIR: Building 2 If you don't measure it, you can't manage it. Green Buildings for Africa, which is part of CSIR: Boutek's Facilities Planning Management Programme, is currently running a project on Water Conservation and Efficiency on the CSIR Campus, as a part of their ongoing work in promoting the efficient use of resources in our commercial buildings.

Water Conservation and Efficiency is the minimization of loss or waste, the care and protection of water resources and the efficient use of water. It is essential because when we look at the growing number of people compare to the available water in South Africa, it is clear that we will soon be running out of available water. So to reduce this problem, water conservation and efficiency should be introduced in all areas where water is used. We can use water efficiently by using plumbing fixtures which use less water, by using more efficient processes, and by using alternative water supplies. Water conservation and efficiency also deals with how water is used by the industrial, commercial, residential and agricultural sectors.

We are now doing a water audit at Building 2. The aim of this project is to develop a strategy to measure water consumption and use, identify possible interventions to improve water use efficiency, select an appropriate intervention and to implement it.

The building was surveyed and it was determined that a water supply tank was installed and a fire hose reticulation. Taps, urinals, cisterns and a dishwasher were identified in toilets, kitchens, laboratories and the canteen kitchen. We have made a urinal water capture device from a 2 litres container connected to a 20 litres container by a 2m length of hosepipe (See photo). The 20 litres container was calibrated up to 10 litres by using a 500ml-measuring cylinder. We used this device to measure water valume/ flush on each urinal. Flow rate and water pressure were measured at each kitchen tap, urinal and toilet tap on each floor.The results are tabulated below.

Equipment

Location

1Range in
Flow rate (L/m) 
or Consumption/flush (L)

Pressure (KPa)

Comments

Kitchen taps

Block B

3 L/m to 6 L/m

400-430

#

Block A

4,2 L/m to 36 L/m

300-430

#,*

Toilets taps

Block B

4,8 L/m to 18 L/m

400-430

#

Block A

6,6 L/m to15, 6L/m

40-150

#, *

Urinals

Block A

0,3 L to 0,8 L

40-150

#

Block B

0,4 L to 2,5 L

380-400

#

Pressure measurements helped to identify the reticulation of the pipes, if the plumbing drawing is not available as in building 2. The water head between the supplying reservoir and building 2 is 44m. By using hydraulics principles, for 1m water head the pressure is 10 Kpa. So for 44m water head a pressure of 440 kpa is expected. For the roof tank a pressure between 40 & 160 kpa is expected, depending on which floor we are measuring on. From the pressure measurements we can conclude whether the supply is from the tank or the reservoir.

We suggest that a urinal should use 300ml per flush, toilet taps should use 3 L/m and kitchen taps should use 4 L/m. If our water using components used the suggested figures we could save up to 50 % of our water and so reduce the water used (and cost) but if you don't measure it, you can't manage it.

A monitoring strategy is now being developed to identify where to install meters so that water use can be accurately logged. This information will be combined with the other audit information to develop a water conservation strategy for the building.

The information and water use criteria developed from the audit of our building will be used to assess other buildings as part of the Green Buildings for Africa Programme.

Article by: Eric Baloyi

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