Thailand Water Bill Calculator

Bill by volume used

Water in Thailand is billed on tiered rates in the same way electricity is, but with far more steps — twelve of them — plus a monthly service charge set by the size of your meter rather than by how much you use. That last part is why a property standing empty still receives a bill. This calculator breaks out every component including VAT.

The good news for most households is that water here is inexpensive. A typical family stays entirely within the cheapest tier, and a monthly bill of a couple of hundred baht is normal.

The water charge is tiered. The first 30 cubic metres cost 8.50 baht each, the cheapest rate and more than enough to cover an ordinary household. Units 31 to 40 cost 10.03 baht, and the rate steps up from there to 14.45 baht for anything above 200 cubic metres.

The twelve-step structure is designed so that light users pay the low rate and heavy users pay progressively more. As with tax brackets, a higher rate applies only to the portion above each threshold, never to the whole amount.

The monthly service charge depends on meter size, not on consumption. An ordinary home with a half-inch meter pays 25 baht a month. A large building on a two-inch meter or bigger pays from 300 baht.

This charge is billed every month even when no water is used, because it covers maintenance of the system and the meter itself.

VAT is 7% on the sum of the water charge and the service charge. Both are published exclusive of tax.

Typical consumption. A household of four generally uses 15 to 25 cubic metres a month, roughly 500 to 830 litres a day, which sits entirely within the cheapest tier. A house with a garden to water or a pool will use considerably more and start reaching the higher steps.

When a bill spikes unexpectedly. If the bill jumps without any change in how much water you use, the most common cause by far is a leaking toilet, which is usually silent and easy to miss. To check, put a few drops of food colouring in the cistern and wait half an hour without flushing. If colour appears in the bowl, it is leaking. A continuously leaking toilet can waste several cubic metres a month.

The other check is to close every tap in the property and look at the meter. If it is still turning, there is a leak somewhere in the system, and it is worth calling the water authority or a plumber.

Which authority serves you. The rates here are the Metropolitan Waterworks Authority’s, covering Bangkok, Nonthaburi and Samut Prakan. Everywhere else in Thailand is served by the Provincial Waterworks Authority, which sets different rates.

If you rent, be aware that many landlords bill water at a flat rate per unit of their own rather than passing on the authority’s bill, in the same way they often do with electricity.