Pools & Water
Pools, ponds and rainwater — volumes, liners, flows and collection, planned before you dig.
Calculators for This Category
- Pool Volume Calculator Pools & Water Rectangle or round, flat floor or averaged depth: cubic metres, litres, US gallons, surface area, fill time and water mass.
- Pond Liner Size Calculator Pools & Water Liner length and width from pond size, depth and edge overlap — plus the underlay area to order with it.
- Pond Volume & Pump Flow Calculator Pools & Water Pond volume in litres and UK gallons, and the pump flow for one full turnover — 1–2 h for koi, 2–4 h for goldfish and wildlife ponds.
Two plumbing-side tools live in Home Maintenance but earn their keep around water: water heater sizing when an outdoor shower or wet room joins the plan, and pipe volume for the fills, drains and pipe runs that move all this water about.
Practical Guides
Water is heavy — 1,000 kg (2,205 lb) per cubic metre — and every water project is a volume problem before it is anything else. A pool's litre count drives heating, treatment and fill planning. A pond's volume sets the pump that keeps it clear. A roof's catchment decides how much a tank can gather. Excavation is the irreversible part: measure and calculate before anyone digs. Treatment chemicals always follow their own product instructions — the tools here are volume only.
Water Volume Units
| Unit | Equals | Where you'll meet it |
|---|---|---|
| 1 m³ (cubic metre) | 1,000 L · 264 US gal · 220 UK gal | Pool specifications, bulk water |
| 1 US gallon | 3.785 L | North American pool and pump specs |
| 1 UK gallon | 4.546 L | UK pond equipment |
| 1 mm of rain on 1 m² of roof | 1 L | Rainwater collection |
The two gallons differ by about 20% — check which one a spec sheet means before sizing a pump. The last row is the whole rainwater arithmetic: the rainwater calculator turns roof area and local rainfall into litres per event and per year.
How Long Does Filling Take?
| Pool | Volume | @ 10 L/min | @ 20 L/min | @ 40 L/min |
|---|---|---|---|---|
| Plunge pool, ~15 m³ | 15,000 L | ~25 h | ~12.5 h | ~6.3 h |
| Family pool, 8 × 4 m × 1.5 m avg depth | 48,000 L | ~80 h | ~40 h | ~20 h |
Typical garden hoses deliver roughly 10–20 L/min depending on pressure, length and fittings; some high-flow setups reach 40. Time yours with a bucket and a watch — the pool calculator does the division for your exact volume.