Low-flush toilets: Use a maximum of 6 litre of water per flush compared with about 13 litres of water used by a standard toilet. These could save up to 22,000 gallons (83,279 litres) of water per year for a family of four.
Low-water urinals: Use a retrofit cartridge lined with bacteria and enzymes that deal with odours between flushes and can reduce the number of flushes to 10 a day. Cartridge costs between Rs 3,000 and Rs 5,000 and needs quarterly replacement.
Dry toilets: Faeces is converted into manure and urine is used in gardens.
Vacuum-based sewer system: Outflows from toilets and kitchens are sucked by a local pump into a household vacuum station, from where they are sucked into a central treatment point. Main lacuna: expensive and energy intensive.
Rainwater harvesting: Uses some or all of a scheme's catchment for capture and storage of rainwater for reuse.
Greywater recycling: Treated grey water for flushing and gardening. In St Petersburg, Florida, USA such water is supplied to over 7,000 establishments.