How many litres do you need? Work it out in a minute
Occupants × daily use per person × reserve days. This page sets out the usual method, a ready table and worked examples for a villa, a 10-unit building, a mosque and a rest house.
- Two-day and three-day table
- Four worked examples
- Help choosing on request
- Any capacity from 2,000 L
We reply within one working hour, Saturday to Thursday.
The formula: people × litres × days
Household use in Saudi homes is usually quoted at 150 to 250 litres per person per day, depending on how the house uses water.
Multiply occupants by daily use per person to get the daily demand, then multiply by two or three days of reserve so supply interruptions or a late tanker do not leave you dry.
Quick example: 6 people × 200 L × 2 days = 2,400 litres.
Ready table at 200 litres per person
For higher use, a large garden for instance, calculate at 250 litres per person; for lower use, at 150. Then choose the next capacity up from your result.
| Occupants | Daily use | 2-day reserve | 3-day reserve |
|---|---|---|---|
| 4 | 800 L | 1,600 L | 2,400 L |
| 6 | 1,200 L | 2,400 L | 3,600 L |
| 8 | 1,600 L | 3,200 L | 4,800 L |
| 10 | 2,000 L | 4,000 L | 6,000 L |
| 12 | 2,400 L | 4,800 L | 7,200 L |
| 15 | 3,000 L | 6,000 L | 9,000 L |
Four worked examples
- Villa, family of 8: 8 × 200 = 1,600 L a day. Two days gives 3,200 L, three days 4,800 L, so a 4,000 or 5,000-litre tank fits.
- Building with 10 apartments, averaging 5 people each: 50 × 200 = 10,000 L a day. Two days gives 20,000 L, three days 30,000 L. For buildings the design engineer sets the final figure and may add a fire reserve where the design calls for one.
- Mosque: there is no fixed figure per worshipper, because use varies with attendance, ablution and cooling. Take daily use from meter readings or the bill. At 3,000 L a day, two days gives 6,000 L and three days 9,000 L.
- Rest house: size for the weekend peak, not ordinary days. 20 guests × 200 L = 4,000 L a day, or 8,000 L for two days, plus pool top-up and irrigation. If it runs on tanker water, choose a capacity that takes a full tanker load.
Do not oversize
A tank much larger than needed leaves water standing longer, which lowers its quality. Two to three days of reserve suits most homes.
If space is tight, keep the capacity and change the shape: we can build on a smaller diameter at a greater length. Septic tanks are sized differently; see the septic tank rules guide.
Frequently asked questions
What size tank for 5 people?
5 × 200 = 1,000 L a day, so 2,000 litres covers two days and 3,000 litres three days.
Is a 5,000-litre tank enough for a villa?
At 200 L per person it covers up to 12 people for two days, or about 8 people for three days.
Should I include the garden and pool?
Yes, if they are supplied from the same tank. Add their daily use to the household figure before multiplying by the reserve days.
One large tank or two smaller ones?
Two tanks let you clean one without cutting supply; one tank is simpler to excavate and install. We can advise based on space and use.
My figure is not in your capacity list.
Enter it as it is. We build to the capacity you need, because capacity is set by length on one of seven diameters.
Related pages
Underground water tanks
Cooler water in summer, no rust or algae, any capacity from 2,000 litres.
Villas and homes
Cooler water in summer, no rust or algae, and a clear split of who digs and who pours.
Buildings and compounds
Large capacities for every unit, crane placement, and a VAT invoice to your entity.
Sizes and dimensions
Diameters, lengths and heights for horizontal and vertical tanks.
Ready for your quote?
Send the type, capacity and city, and we reply within an hour.