Calculator Inputs
Example Data Table
| Scenario | Usage (m³) | Garden share | Pricing type | Fees | Estimated total |
|---|---|---|---|---|---|
| Small beds, light watering | 6.0 | 70% | Tiered | Service + meter | Varies by rates |
| Medium lawn, weekly schedule | 14.0 | 85% | Tiered | Service + meter | Varies by rates |
| Large landscape, summer peak | 28.0 | 95% | Flat | Service + meter | Usage × flat rate + fees |
Formula Used
- Usage(m³) = Current − Previous, or converted from liters/gallons.
- Adjusted usage = Usage × (1 + Leak%/100).
- Garden usage = Adjusted usage × GardenShare%/100.
- Water charge = sum of tier charges, or Garden usage × FlatRate.
- Subtotal = water charge + fixed fees + sewer surcharge.
- Total = (Subtotal − Discount) × (1 + Tax%/100).
How to Use This Calculator
- Choose Meter readings or Direct volume.
- Enter usage and set your garden share percentage.
- Select tiered or flat pricing from your bill.
- Add fixed fees, any sewer surcharge, rebates, and tax.
- Press Submit to see results above the form.
- Use Download CSV or Download PDF for reports.
Meter readings and volume conversion
Use two meter readings in cubic meters, or enter a direct volume. Liters convert by dividing by 1,000, while US gallons convert using 3.785 liters per gallon. The calculator standardizes everything to m³ so pricing stays consistent across seasons and watering methods, including drip lines, sprinklers, and hand watering. For checks, 1 m³ equals 1,000 L and about 264 gallons.
Garden share and leak adjustment
Many homes share one meter for indoor and outdoor water. Garden Share allocates only the irrigation portion, so costs match landscaping budgets. Leak or extra usage adds a percentage before pricing, helping you model stuck valves or broken emitters. Example: 12 m³ usage with 10% leak becomes 13.2 m³. If only 80% feeds the garden, priced volume becomes 10.56 m³.
Tier bands versus flat pricing
Tiered rates reflect conservation pricing: the first block is cheaper, later blocks cost more. With limits 10 and 20 m³, and rates 0.90, 1.20, and 1.60 per m³, a 16 m³ garden share charges 10×0.90 + 6×1.20 = 16.20. Flat pricing multiplies all garden m³ by one rate. Use tiers when your bill shows “Block 1, Block 2” lines.
Fees, surcharges, discounts, and tax
Fixed service and meter fees are added after the water charge. A sewer surcharge can be set to 0% for irrigation-only billing, or higher where rules apply. Discounts model rebates or seasonal credits, applied before tax. This order mirrors many utility invoices and keeps totals comparable month to month. Track fee changes separately, because they can shift totals even when usage stays stable.
Benchmarks for planning irrigation costs
Beyond the grand total, the calculator returns cost per day and cost per 1,000 liters for the garden share. These benchmarks help compare schedules. If 18 m³ garden use totals 42.00 in your currency over 30 days, the average is 1.40 per day and 2.33 per 1,000 liters. Use the benchmarks to test mulch, shade cloth, or shorter run times and quantify savings.
FAQs
1) How do I choose between readings and direct volume?
Use readings if your bill shows start and end meter numbers in m³. Use direct volume when you track irrigation separately, such as tank refills or smart controller reports. The calculator converts units and prices the garden share the same way.
2) What if my meter is in gallons or liters?
Select Direct volume and choose liters or US gallons. The calculator converts to cubic meters internally using 1,000 L per m³ and 3.785 L per gallon. This keeps tier limits and rates comparable.
3) How should I set Garden Share?
If the meter covers the whole property, estimate the irrigation portion as a percent. For example, 60% in cooler months and 90% in summer. Adjust until the garden-only total matches what you observe in seasonal bills.
4) Does the leak percentage replace real leak detection?
No. It is a planning factor that increases usage before pricing. Use it to model suspected overwatering, stuck valves, or unknown losses. If the number is high, inspect zones, timers, and emitters to confirm.
5) When should I use a sewer surcharge?
Some utilities charge sewer based on total water, while others exclude outdoor use. If outdoor water is excluded, set the surcharge to 0%. If your invoice adds a sewer percentage to irrigation, enter that percentage here.
6) What do the CSV and PDF downloads include?
They export your latest calculation, including usage, garden volume, fees, discounts, tax, and the final total. Run a calculation first, then use the buttons in the results panel to download a shareable summary.