How Much Water Does a Household Actually Need?

Two very different numbers

Ask how much water a household needs and you get two answers that are both correct. The World Health Organization puts basic survival and hygiene needs at around 50 to 100 litres per person per day. Households on unrestricted municipal supply commonly use two to four times that, because nobody meters a shower by hand.

For planning a bulk water delivery, the useful figure sits between them. A household of four using water deliberately — drinking, cooking, washing, laundry and sanitation, with the garden left alone — will typically move through 400 to 600 litres a day. That is the number worth working from when you decide what to order.

Where the water actually goes

The intuition that drinking water matters most is wrong by an order of magnitude. Drinking and cooking are a small fraction of household consumption. Everything else is the real load.

• Toilet flushing — commonly the single largest use in a household, at roughly 6 to 9 litres per full-cistern flush.
• Showering and bathing — a shower typically runs 6 to 12 litres a minute; a filled bath is often 80 to 150 litres.
• Laundry — a washing machine cycle is commonly 40 to 80 litres.
• Washing up and cleaning — modest individually, significant across a day.
• Drinking and cooking — usually under 10 litres per person per day.
• Garden and pool — unbounded, and the first thing to stop when supply is short.

What that means for a tanker load

Using 400 to 600 litres a day as the planning band for a careful household of four:

• A 2,500 litre delivery covers roughly four to five days.
• A 5,000 litre delivery covers roughly eight to ten days.

Halve those figures for a household using water normally rather than carefully, and adjust for occupancy. A house with six or seven people in it — common where there are lodgers, extended family or student tenants — goes through a load considerably faster than the stand size suggests.

How to stretch a delivery when supply is unreliable

None of this is about rationing for its own sake. It is about the difference between a load lasting five days and lasting nine, which is the difference between one delivery and two.

• Put a bucket in each bathroom for flushing rather than using the cistern for every flush. This alone is often the largest single saving available.
• Shower rather than bath, and shorten the shower. A two-minute reduction saves more than most other measures combined.
• Run the washing machine only on full loads while supply is interrupted.
• Fix dripping taps and running toilets. A running cistern can waste more per day than a person uses.
• Stop garden watering entirely, and cover the pool to slow evaporation.
• Keep drinking and cooking water in separate closed containers so it is never the thing that runs out.

Sizing your storage properly

If interruptions are a normal part of life at your property rather than an exception, the real fix is storage capacity rather than delivery frequency.

A household that can hold 5,000 litres can take a single delivery and stop thinking about water for over a week. A household with 2,500 litres of storage is ordering twice as often, paying more per litre, and arranging access twice as many times — for the same water.

Related pages

• Residential water delivery
• 5,000L water delivery — US$50
• Bulk water prices in Harare