Estimate a Sri Lanka household water bill with domestic, samurdhi, and tenement tariff comparisons.
Quick planning, rough comparisons, and checking whether your assumptions are in the right range before you rely on final quotes or advice.
Review the assumptions below, then compare with related calculators if your decision depends on rates, eligibility, or provider-specific rules.
How this calculator works
- Pick the household category, enter the water units used, and set the bill period in days.
- The calculator prorates the tariff blocks and service charge from a standard 30-day schedule so shorter or longer bill periods can be estimated.
- Results are shown across three tariff periods to mirror the public comparison style used by Sri Lankan water-bill tools.
Worked example
For 18 units over 30 days on the Domestic tariff, the current estimated bill is LKR 2,117.
Important assumptions
- This version focuses on the three household paths shown on the public calculators: Domestic Samurdhi, Non Samurdhi Tenement Garden, and Domestic.
- The current tariff table is modeled from the NWSDB gazette dated August 21, 2024. Numbers.lk labels that same comparison block as 'After Aug 2024' and also shows a January 17, 2025 note, which appears to be a site note rather than a separate published tariff table.
- For the 2023 and 2024 tariff rows, the calculator now shows SSCL and VAT separately. VAT is applied after SSCL, which matches the standard invoice treatment for taxable utilities.
- Official bills can still differ due to arrears, rebates, sewerage, or provider-specific bill adjustments that are outside this simplified calculator.
Methodology and review
Shared calculator template reviewed for formula clarity and on-page transparency.
Editorial review focuses on practical accuracy, assumptions, and user-facing clarity.
Lankacalculator publishes these tools for practical planning, with the expectation that users will validate important decisions against primary sources.
How this calculation is produced
- This calculator uses the formula and assumptions defined for the page to turn your inputs into a practical planning estimate.
- Results are designed to be quick, transparent, and useful for first-pass decisions rather than provider-specific final quotes.
- The output should be treated as a directional estimate until you check the relevant rates, rules, or assumptions behind your case.
What to verify before relying on it
- Check that your units, assumptions, and scenario match the real decision you are trying to make.
- Compare the output with a second trusted source if the result affects money, health, or compliance.
- Use official provider, government, or expert information whenever the estimate needs to become a final decision.
When this tool is useful
- Use this for quick planning, early comparisons, and first-pass estimates.
- Use it when you need a decision baseline before opening a spreadsheet or asking for quotes.
- Use it again whenever the main assumptions behind the calculation change.
How to read the result
- Treat the primary result as an estimate that depends on the inputs and formula assumptions.
- Compare supporting metrics, not just the headline number, before making a decision.
- If the output affects spending or health decisions, validate it with a second source.
Common mistakes
- Entering optimistic assumptions and reading the result as certain.
- Comparing results from different tools without aligning units or definitions.
- Using one scenario only instead of testing a few realistic alternatives.
Good next steps
- Run a second scenario with stricter assumptions.
- Compare the output with related calculators or guide pages in the same topic.
- Use the result to narrow options, then confirm details with real provider or expert information.
FAQ
Are these calculators free?
Yes. lankacalculator tools are free to use and designed to be quick to access without sign-up.
How accurate are the results?
The calculators use clear assumptions and formulas, but results are estimates and should be checked against official documents or provider terms.
Can I use this on mobile?
Yes. The layout is built to work cleanly on phones, tablets, and desktops.
Do you store my inputs?
No account is required for these tools, and calculator inputs are not stored as user profiles in this v1 setup.