Calculate water costs 2026 from the actual unit of your home.
The housing and utility tax rates are shown in the table 1-3, with service charges, raw water and VAT.
Suitable for monthly budgeting and comparing before-after water savings • Updated on: 21 May 2026
Water Bill Calculator
The Water Bill Calculator estimates a tax and statutory rate estimate for your scenario from the quantities, rates, period, units and other assumptions requested on the page. Replace the example values with your own water bill figures and recalculate after changing an assumption. Treat it as a planning estimate and independently verify the current rule or provider terms.
Enter the number of units of water used per month and choose the water supply according to the area of use. The system will summarize the water costs by step, separately for water, service, raw water and the total before/after VAT as Thai baht without the minimum contamination of water users type 2.
Trust information
Use reference information from Thai official agencies. and display results to help plan before making decisions
Last updated: 19 Apr. 2026
source
- Water Supply Corporation (WSC): Rates of water and monthly service charges
- Regional Water Supply Authority (GWP): Table of Rates for Water
- Regional Water Supply (GWP): Water User Classification
Assumptions and things to note
- The calculation results are estimates based on the data entered by the user and the latest official rate table used as reference, without using the minimum 150 baht of water users of the type 2 with residential accounts.
- Actual bill amounts may differ slightly from the estimates and the water meter day-to-day.
Formula used for calculation
- Ladder bets = total (number of units in each period x the bet rate of that period)
- In the case of the GPU. Residential type 1 no limit 150 baht; the minimum is of the water user type 2 so it is not taken positive in this tool
- The case of the GPN. plus monthly service fee according to the size of the water meter and the raw water price 0.15 baht / lb. m.
- Total before VAT = Water Level + Service Fee + Raw Water (only items used with the provider and account type selected)
- Net total = total before VAT + VAT
Read the detailed description with examples in Thai baht in the commentary below.
Learn more from our article.
The formula used to calculate the water value.
Total water charge = Level water charge + Service/related raw water charge + VAT 7%
Water consumption rate (household level):
- 0–30 l/min. = 8.50 baht/l/min.
- 31–40 l/min. = 10.03 baht/l/min.
- 41–50 l/min. = 10.35 baht/l/min.
- From 51 lb. m. use the next rate range according to the GPN table until more than 200 lb. m.
The service charge is calculated by the meter size (starting at 25 baht for 1/2 inch meters) and the raw water charge 0.15 baht/L. m.
Example of a water value calculation
Example 1: Water consumption 15 l/month (household)
- The water value = 15 × 8.50 = 127.50 baht
- Service charges for metric 1/2 inch 25 baht + raw water charges 2.25 baht
- Including VAT 154.75 baht + VAT 10.83 baht = 165.58 baht
Example 2: Water consumption 35 l/month (household)
- The water value = (30 × 8.50) + (5 × 10.03) = 305.15 baht
- Service charge 25 baht + raw water charge 5.25 baht = 30.25 baht
- Including VAT 335.40 baht + VAT 23.48 baht = 358.88 baht
Example 3: UPS Table 3 Water Use 5 L/month (residential)
- The water value = 5 × 10.20 = 51.00 baht
- Residential type 1 no minimum 150 baht of type 2
- The water charge 51.00 baht + VAT 3.57 baht = 54.57 baht
How to calculate the water value
- Water meter reading: Check the water bill or read the meter directly
- Calculation of water consumption = current meter - previous meter (in l/m)
- Select a category: Household (G. P./G. U. P.) or Small Business
- Calculate the water charges according to the rank of the unit.
- Add service charges and raw water when the account is GPN; do not add values that are not in the account type
- Multiply 1.07 (VAT 7%) to get the total payment.
- Compare the actual bill and the usage log to check for leaks.
References:Water Supply and Sanitation (WSS): Rates and Services ·The Regional Water Supply Authority (GWP): Table of Water Rates
General errors in calculating the water value
When calculating the pipe value:
- Does not understand "lb/cm" (cubic metres)
Household water consumption 10 lb/month = 10,000 litres (very large) 1 person should use 5-10 lb/month 1 lb/month = 1,000 litres See units from MWA/PWA disclosure sheet - I don't know if there's a fixed charge.
Water consumption 8 lb. m. × water rate = gets one number but actually pays more because of maintenance (~25-30 baht/month) Total water charge = (lb. m. × rate) + maintenance - Incorrect staircase ratio.
For example, the KPN housing project of 35 sqm is calculated as (30 x 8.50) + (5 x 10.03) = 305.15 baht, not 35 x 10.03 baht as a whole, and includes service charges, raw water and VAT. - I don't understand the meter reading formula.
Meter last month 1,234 lb. m. This month 1,245 lb. m. Water used = 1,245 - 1,234 = 11 lb. m. (easy straightforward) - Forget about the damages, the fines, if you don't pay or the meter breaks.
Not paying water charges 2-3 month MWA/PWA will charge damages, large interest, pay water charges on time, if there is any problem contact MWA/PWA to discuss
Frequently asked questions
How does the housing tax work?
Why is the water bill some months more expensive than the 50 unit?
What's the reason for the difference in the calculated amount and the actual bill?
Do you have to add VAT every time?
Common errors in calculating the water value to avoid?
English calculator guide
How to use the Water Bill Calculator
Use this page to test a specific water bill scenario. Enter your own values in the calculator above, review the units beside each field, and recalculate after changing an assumption. The result updates the water bill estimate instead of relying on a generic example.
- Build a baseline water bill case with figures that match your situation.
- Run a second water bill case after changing the rate, period, quantity or other key assumption.
- Record the difference between the two water bill results and the input responsible for it.
Inputs for the water bill estimate
For this water bill calculation, check the quantities, rates, period, units and other assumptions requested on the page. The result is designed to show a tax and statutory rate estimate for your scenario, not a guaranteed provider price or official decision.
How the water bill result is calculated
The calculator applies the displayed statutory rates, thresholds and allowances to the figures you enter. Reusing the same water bill inputs will produce the same estimate, which makes the page suitable for controlled scenario comparisons.
Checks for a water bill decision
Confirm any current rate, threshold or provider rule that could change the final amount. For water bill, Use the estimate to plan a household or service cost. Actual charges can differ because of provider tariffs, minimum fees, taxes, location and billing-period adjustments. Because this calculation can affect an important financial, legal or health decision, independently verify the inputs and current rules before relying on the result.
- Language QA
- Terminology, numeric values and calculator controls checked
- Calculator scope
- Tax and statutory rate
- Last English review
- 26 July 2026