This is with reference to the letter “Conserving water” (June 9). I agree that we should make serious efforts to conserve water.

The suggestion that “a billing system” should be introduced for water consumption on the same lines as for electricity, gas and telephone is a good proposal, but then this will involve meters installed for each housing unit, which may not be possible due to the huge capital investment involved.

If meters are to be installed for say, one million housing units in Karachi, with a population of about 17 million, and if each meter installation costs Rs10,000, then the capital investment required for KWSB will be Rs170,000 million. This is a huge amount for KWSB to generate and spend.

To accrue the benefits of metering consumption, at the most meters could be installed by KWSB for all new constructions of highrise buildings and for newly-built houses in elite housing societies who are big consumers of water, as compared to houses in slum areas and in low- and middle-class societies.

Gradually meters could be installed in existing high-rise buildings and in houses in elite societies, for example Defence, Clifton, etc. Along with this, the KWSB will have to reorganise to provide staffing for meter reading and billing.

I agree to the suggestion that “rain harvesting” should be practiced so that rain water is conserved and not allowed to be wasted in storm drains. But Karachi has rains only for a few days in a year for which special construction cost for rain water collection will not be worthwhile.

Rain harvesting is feasible for high-rainfall areas as Lahore and in the north. Each house in such areas should have its flat roof specially constructed, to be sloped and bunded, so that rain water is collected on the roof and then drained from the roof to an underground grey-water storage tank.

In Chennai, India, rain harvesting has been made mandatory for all citizens. If one does not follow this rule, then the power supply to his house is disconnected as a penalty. As a result, the water-shortage problem has been solved with no cost to the government.

To conserve water, water in our rivers and canals should also not be allowed to drain into the sea. It has been suggested that small dams and reservoirs should be built as needed.

In addition, I suggest that we should recycle “grey” waste water which is generated in residences and industry. “Grey-water” is waste water without human waste and without toxic substances, as generated from hand basins, kitchen sinks, showers, baths, clothes-washing areas, etc. “Black-water” is waste water containing human waste and toxic substances.

Grey-water can be recycled in homes/flats in the flush tanks of toilets and for gardening and washing floors, instead of using fresh water. Using fresh water for flushing toilets is criminal; especially when there is such an acute shortage of water.

Grey-water can be recycled by installing grey water plumbing lines, drain and supply, for new construction.

Existing plumbing lines in a house can easily be modified to have separate grey-water plumbing lines draining from hand basins, kitchen sinks, baths and showers to a grey-water storage tank and from it supplying to flush tanks, gardens, lawns, etc.

To use grey-water immediately, just connect the kitchen sink's outlet to a plastic hose discharging in to a drum or directly in to your lawn and flower beds. Thus water will be conserved instead of watering the lawn/ garden with fresh water.

As a first step in conserving water, the KBCA should approve high-rise buildings' plans only if there is a separate grey-water plumbing system provided in each plan. The same should be done in the case of elite housing societies, e.g. in Defence, Clifton, PECHS, etc.

The government could also encourage grey-water plumbing by reducing tax on properties with such plumbing.

A. Rahim
Karachi