Repairs & how-to
Common pump installation mistakes (and how to avoid them)
A surprising share of pump problems, weak pressure, short-cycling, early failure, actually start at installation. None of the fixes are hard; they’re just easy to get wrong if you don’t know to look. Here are the ones that cause the most grief.
Undersized pipework
The single most common flow-killer. Running a pump into pipe that’s too narrow chokes it, and you get weak pressure no matter how good the pump is. Match the pipework to the pump’s inlet and outlet size (a pump with a 25mm outlet wants at least 25mm pipe, not a 20mm run), and keep long runs and tight elbows to a minimum. A pump can only push what the pipe lets through.
Air on the suction side
Any loose fitting, or a suction line that isn’t airtight, lets the pump draw air instead of water, so it loses prime and struggles. Every joint on the inlet side must seal. Use thread tape properly and check every fitting.
No pressure tank, or a waterlogged one
Without a pressure tank, or with one that has lost its air charge, the pump starts every time you crack a tap, which is short-cycling, and it wears the pump out. Fit a correctly pre-charged pressure tank, set a couple of psi below the pump’s cut-in (see our pressure-tank guide).
A foot valve where it’s needed
On a pump drawing up from a tank or well, a foot valve at the bottom of the suction line keeps it primed between uses. Leave it out and the line drains back every time, so the pump loses prime (see our check-valve guide). Like any one-way valve it has a flow direction, so fit it with the arrow pointing toward the pump.
Poor siting
- Not on a firm, level base, which causes vibration and noise.
- Not housed against weather, frost and insects, or with no ventilation.
- No isolation valves either side, so servicing means draining the whole system.
- A suction lift of more than about 7 metres, a surface pump can’t draw water higher than that.
Boosting the mains without checking the rules
Connecting a pump directly to the town mains isn’t permitted everywhere in Australia, and the rules vary by water authority. A break tank is the universally accepted setup. Check what applies in your area before you plumb it in.
Safety: Most home pressure pumps simply plug into a 240 V power point; make sure the circuit is RCD-protected. If a pump is hardwired or there’s no power point nearby, that part is an electrician’s job. Connecting to the town mains is regulated by your water authority and needs a licensed plumber.
A pump that shows you the install is right
Once a Grewa pump is running, the app shows you it’s holding pressure steadily and not short-cycling, the quickest way to confirm the install is sound. If the pressure tank is waterlogged or there’s a slow leak, the readings and slow-leak detection surface it early rather than months later.
Common questions
What size pipe should I use?
As a rule, match or exceed the pump’s inlet and outlet size, and never neck it down to a smaller pipe. Undersized pipe is the most common cause of disappointing pressure from a perfectly good pump. Longer runs and more bends also cost pressure, so keep them sensible.
Do I really need a pressure tank?
For a pressure system, in practice yes. Without one the pump cycles on and off every time you use a tap, which wears it out fast. A small, correctly pre-charged tank makes the whole system calmer and longer-lived.