Water & tank care
How to check how much water is in your tank
Knowing how much water you have actually got in the tank is the difference between managing a dry spell and being caught out by it. There’s a method for every budget, from free to fitted.
The simple ways
- Tap and listen. Knock up the side of the tank; it sounds duller below the water line than above. Rough, but free.
- The dipstick. A clean stick or weighted tape lowered through the inlet tells you the depth of water.
- A sight tube. A clear vertical tube plumbed to the base of the tank shows the level at a glance, like a fuel gauge.
- A float gauge. A float on the water moves a dial or indicator on the outside of the tank.
Turning depth into litres
Most tanks are close enough to a cylinder that the water level maps neatly to volume: half the height is roughly half the water. Your tank’s specs will list its full capacity and dimensions, so a depth reading gives you a fair estimate in litres. Slimline and odd-shaped tanks are less linear, so use the maker’s chart if they provide one.
The smart option
A water-level sensor reads the depth continuously and sends it to your phone, so you can see the tank from anywhere and get a heads-up before it runs low. It’s the easiest way to actually keep on top of it, rather than remembering to go and check.
Common questions
How accurate is knocking on the tank?
It will tell you roughly where the water line is, which is often enough. For a real number, a dipstick or a fitted gauge is far better.