Cheaper in the capital

A household in Bangkok pays ฿255 in water charges for 30 cubic metres a month. The same 30 cubic metres from the Provincial Waterworks Authority costs ฿452.

Both prices are set by state enterprises under the Interior Ministry. Thailand has no national water tariff. Which one you pay depends on which side of an administrative line you live.

Three systems, not one

• The Metropolitan Waterworks Authority supplies Bangkok, Nonthaburi and Samut Prakan.
• The Provincial Waterworks Authority supplies the other 74 provinces, through 234 branches, where it operates.
• Everywhere else, local government runs the water: municipal systems, sub-district systems and village systems, which the provincial authority’s own guide lists as outside its service.

Each sets its own price. The first two publish theirs. The third does not, in any one place this site could find.

Bangkok’s table

The metropolitan authority’s household tariff has been in effect since December 1999. For a residence:

• ฿8.50 a cubic metre for the first 30;
• then ฿10.03 for 31–40, ฿10.35 for 41–50, rising in steps to ฿14.45 above 200.

VAT is not included. A raw-water charge of 15 satang a cubic metre, passed to the Royal Irrigation Department, has been added since June 2004. A monthly service fee depends on the meter: ฿25 for a half-inch meter, the smallest size.

In April 2023 the authority’s then governor said the tariff had not risen in 23 years and was under review. The deputy minister overseeing it said there would be no increase under that caretaker government. On 8 October 2026 the authority’s tariff page still showed the 1999 table.

The provinces’ table

The provincial authority publishes three tables — one for areas served under private investment partnerships and Chon Buri, one for Phuket, Samui and Phangan, and one for everywhere else. For households, all three carry the same rates:

• ฿10.20 a cubic metre for the first 10;
• ฿16.00 for 11–20;
• ฿19.00 for 21–30;
• ฿21.20 for 31–50.

Above 50 cubic metres a month, a household is charged the small-business rate from the 51st cubic metre.

In April 2023 the authority’s deputy governor said it had not raised prices in more than ten years, that costs had risen 15–20%, and that an earlier request to the Interior Ministry had not been approved.

The same water, side by side

This site’s arithmetic from the two published tables, water charge only:

The gap widens with use, because Bangkok’s first price runs flat to 30 cubic metres while the provincial price steps up at 10 and 20. On top of the water charge, the metropolitan bill adds the meter fee, the raw-water charge and VAT. The provincial authority’s terms provide for a general service charge, but its schedule was not found on its site.

Not a mark-up

The provincial authority does not present its price as a profit. Its customer guide for the 2026 edition says:

• households and similar users taking no more than 50 cubic metres a month are about 83% of its customers, and pay on average less than it costs to supply them;
• small businesses and government users pay about cost;
• large businesses and industry, about 3% of customers, pay more than cost.

On the authority’s own description, then, the provincial household is already subsidised by its larger customers, from a higher starting price than the capital’s. Why the two starting prices differ is not explained on either authority’s tariff page.

Where the subsidy runs out

Holders of the 2026 state welfare card get help with water from either authority on the same terms, as each authority’s head described them:

• a bill up to ฿100 is paid in full;
• a bill between ฿100 and ฿315 is reduced by ฿100;
• a bill over ฿315 gets nothing.

The ceiling is the same number of baht everywhere. The water it buys is not. A household using 25 cubic metres a month pays ฿212.50 in water charges in Bangkok, inside the ceiling even with the fee and VAT added. In the provinces the water charge alone is ฿357, and the subsidy stops. (This site’s arithmetic.)

The third tier

For villages on their own systems, there is no table to compare. Prices are set locally, and no national list of them was found.

What has been counted is quality. Of 10,271 village systems the Department of Health sampled between 2018 and 2024, 420 — about 4% — were certified clean enough to drink at home, the public health ministry said in January 2025. The country has 69,028 village systems.

What this adds up to

Tap water in Thailand is priced by where you live, by different public bodies. The capital’s table dates from 1999; the provincial authority said in 2023 that its own had not risen in more than ten years.

This is article 65’s point, made in a monthly bill. The capital gets the cheapest supply of a basic service, and the province pays more for the same cubic metre. And it is article 92’s limit on the second finding: a subsidy that reaches everyone at the same baht is universal, but it is not adequate in the same way everywhere. At 25 cubic metres a month, the same subsidy covers the Bangkok household and not the provincial one.

Nothing in this article is a judgement on either utility’s costs, which neither publishes alongside its tariff.

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Common misconceptions

“Thai tap water costs ฿8.50 a unit.” That is Bangkok, Nonthaburi and Samut Prakan, for the first 30 cubic metres. The provincial authority’s first rate is ฿10.20, rising to ฿19.00 by 30 cubic metres.

“Bangkok’s rates went up recently.” The metropolitan authority’s household table has been in effect since December 1999.

“The provincial authority overcharges.” Its own guide says households pay on average below cost, subsidised by large users.

“The welfare-card water discount is worth the same everywhere.” It is the same in baht. A provincial household reaches the ฿315 cut-off at a lower volume.

“Village water is cheaper.” Some may be; there is no published national table. On the Department of Health’s sampling, about 4% of village systems were certified safe to drink.