Pakistan is currently one of the top five countries which are already severely impacted by climate change and, with the weather predicted to increasingly swing from periods of warmer and wetter to extended bouts of drought, water saving and water harvesting methods are essential.

Rainwater harvesting is a simple, extremely effective way of saving otherwise wasted water which can be used both inside and outside the home, office, school, hospital, industrial unit, etc.

• As little as a 10-minute shower can, provided the collection system is fully maintained, supply up to 20 gallons of water from an average house roof with a harvesting system leading into just one tank.

• With a water tank placed at each corner of a regular house, four tanks in all, 80 gallons of water can accrue from a reasonably heavy shower of 15 minutes duration.

• Installing a rainwater harvesting system is simple and cost-effective.

• For sloping roofs all that is required is firmly fixed guttering, running around and just slightly underneath roof edges, leading to down-pipes at roof corners.

• These down-pipes should drain into drums or tanks, the latter can be either above ground or underground, from which, by hand or by pump, water is drawn as needed.

• It is sensible to install filters, a squished together handful of mosquito netting works well, in the top of the down-pipes to prevent twigs, leaves, etc. from blocking them.

• A filter should also be placed over the down-pipe exit, a wired-in piece of nylon stocking or fine muslin cloth works well, to exclude particles from entering the storage drum/tank.

• Rainwater is ideal for garden and utility use and can, with the assistance of a plumber, be pumped into bathrooms for flushing and bathing purposes.

A wonderful, yet largely ignored, source of water is the condensation that drips, to the annoyance of many, from air conditioning units.

• Depending on the size of the air conditioning unit, it will drip from approximately two to eight gallons of water each day.

• The amount of condensation-water produced increases in high humidity when, in conjunction with cooling a room interior, the air conditioner doubles as a de-humidifier.

• This condensation water is perfectly clean, cleaner than most tap water, and great for garden or utility purposes.

• If a drainage pipe is connected directly to the unit, this pipe can be run into a convenient area of garden to drip feed plants.

• In the absence of a drainage pipe, collect the water in buckets and use it anywhere in the garden, for car washing, etc.

• Do not panic about ‘Legionnaires’ disease’: This rare disease is caused by a bacterium that can form in the stagnant water inside huge air conditioning units such as those used in hotels and hospitals. There has never been a case reported of it occurring in the kind of air conditioners used in homes or in individual offices.

As for piped in water: reduce and recycle are the rules.