Installing a water pump and tank: how to choose the right size for your house, for strong water pressure without interruptions

Have you ever been enjoying a shower when the water suddenly slows to a trickle, or barely comes out at all upstairs? These problems are easy to fix by installing a water tank and pump that suit your home. The question is how to know what size to choose — not so small that you run out of water, and not so big that you waste your budget. Here are some simple formulas.

1. How to size a water tank for the people in your home

Tank sizing is based on the average water use of people in Thailand, which is about 150–200 litres per person per day You should keep a reserve for at least 1–2 days in case the mains supply stops. The simple formula is: Number of occupants x 200 litres x number of reserve days = tank size (litres)

• Home with 1-2 people: a 500 – 700 litre tank is recommended
• Home with 3-4 people: a 1,000 – 1,500 litre tank is recommended
• Home with 5-6 or more people: a tank of 2,000 litres or more is recommended

2. Choosing the right pump wattage for your house

When choosing the power (watts) of an automatic water pump, look mainly at the height of the house and how many bathrooms may be in use at the same time, so the water pressure stays even at every outlet.

• Single-storey house (1-2 bathrooms): use a 100 – 150 watt pump
• Two-storey house (2-3 bathrooms): use a 200 – 250 watt pump
• 3-4 storey house, or one with a rain shower: use a pump of 300 – 400 watts or more

3. Key checklist before you install

A home water system needs good planning from the start so it works efficiently and is easy to maintain over the long term. Check these points before installing:

• Tank base: must be a level, solid concrete slab that can carry the weight of a large tank without settling
• Bypass piping: run a bypass line for power cuts so you can still use mains water at normal pressure without going through the pump
• Installation location: should be in the shade with good ventilation; the pump should not sit in strong sun or be exposed directly to rain

Precautions and safety advice

You can work out the equipment sizes yourself, but the actual installation — especially the electrical supply for the pump , which needs its own breaker and a properly installed earth wire, as well as the structural base that carries the tank's weight and the connection to the main water pipe — is best left to a specialist tradesperson for maximum safety, and to prevent current leakage, burst or leaking pipes, or the tank base settling and causing damage later.