From a tank reading to a practical plan
- Measure your tank. Use its rated capacity, or estimate geometric capacity from internal dimensions.
- Check your current water. Enter a volume percentage or calculate stored litres from the water depth.
- Set your daily use and reserve. Get a no-rain estimate of how long the available supply lasts.
- Compare your options. Explore roof collection and check delivery timing and headroom.
What these calculators assume
Results depend on your inputs. Water use is constant in each calculation; rainfall and deliveries occur only when you enter them. A reserve is a planning buffer you choose. Estimates do not replace checking your tank or confirming supplier availability.
These tools use litres, metres, square metres and millimetres. They do not assess drinking-water quality or certify water required for firefighting. All calculations run in your browser. Optional site analytics is controlled through your existing privacy choice.