A station will not turn off, or a sprinkler weeps constantly

What has gone wrong

A station keeps running after the controller has moved on, or a sprinkler weeps continuously when nothing is scheduled at all. Either way the valve is being held open when it should be shut.

That is nearly always the diaphragm. A piece of grit is holding it off its seat, or the rubber has perished and no longer seals. Occasionally it is simpler than that — a bleed screw or a solenoid left loose after somebody manually opened a valve, which holds it open exactly the same way.

This one costs you money every hour it is left. A weeping valve on a two days a week roster is also the kind of thing an inspector notices, and the fine is $100.

Why this happens in Perth

Bore water is the reason this fault is so common here. Perth's domestic bores draw roughly 90 gigalitres a year — about 22% of the groundwater used across the metro area — and that water carries fine sand and dissolved iron straight through the valve. Sand lands on the diaphragm seat. Iron stains everything orange and stiffens the rubber.

Then the system sits still from 1 June to 31 August. Three months of no flow lets whatever is in suspension settle out onto the seat, and lets a diaphragm that was already tired dry out and take a set. On 1 September it does not reseal.

Scheme water systems get this too, just later and less often.

Is this a DIY job?

Yes. Everything below is 24V AC or purely mechanical, which is the part of a reticulation system a homeowner can safely work on.

Check the free things first

One. Turn the controller off completely. If the station still runs with the controller off, the fault is at the valve, not in the wiring or the programming. That is what you want to know before you start digging.

Two. Go to the valve and check the bleed screw and the solenoid are both done up. If somebody manually opened that valve — including you, doing the test on the previous page — and did not close it properly, that alone will hold it open. Hand-tight is enough.

Three, and this is the one that usually works. Rinse the diaphragm.

1. Turn the water off at the tap or master valve.
2. Undo the bonnet screws — usually four, sometimes six. Keep them; they are a fiddly size to replace.
3. Lift the bonnet straight up. There is a spring under it. Note which way it sits.
4. Lift out the diaphragm and look at the seat underneath. Sand, a leaf fragment, a bit of gravel — anything sitting on that ridge will hold the valve open.
5. Rinse both the diaphragm and the seat clean. Check the small pilot holes through the diaphragm are clear; a blocked one is its own version of this fault. A bit of wire or a bristle will clear it. Do not enlarge it.
6. Put it back the same way up, spring in, bonnet down, screws in evenly.

If it seals, you have fixed it for nothing. That happens often enough that trying it first is the sensible order, and we would rather tell you that than sell you a part you did not need.

If rinsing did not fix it

The rubber has gone. A perished diaphragm feels stiff rather than supple, and often has a permanent ring pressed into it where it has been sitting on the seat.

Here is the part worth knowing before you buy anything.

A replacement diaphragm on its own is about $50.60. A complete Hunter PGV 25mm valve — new body, new diaphragm, new everything — is $32.50 to $34.89. Both verified against Perth Irrigation's retail pricing on 5 August 2026.

The whole valve is cheaper than the part inside it. That is not a mistake and it is not a trick; it is what happens when one item sells in volume and the other does not. If your valve body is sound and the threads are good, a diaphragm is still the tidier repair and there is nothing wrong with doing it. But do not pay $50 for a diaphragm believing you are taking the cheap option, because you are not.

Check the brand moulded into the bonnet before you buy either one. Diaphragms are not universal, and Toro and Irritrol share a thread with each other but not with Hunter.

What it costs

Rinsing it: nothing.

New diaphragm: around $50.60. Complete valve: $32.50 to $34.89. Both verified, Perth Irrigation, 5 August 2026.

Doing nothing: a weeping valve runs continuously. On a two-day roster that is also a compliance problem, and inspectors are out seven days a week.

If you pay somebody. Perth callout rates are not something we have verified, so we will not quote one. Ring two and ask.

Common questions

Why does my sprinkler station keep running after the controller turns off?

The valve is being held open. Nearly always grit on the diaphragm seat or perished diaphragm rubber, and occasionally just a bleed screw or solenoid left loose.

Can I fix a weeping retic valve without buying anything?

Often, yes. Turn the water off, undo the bonnet, lift out the diaphragm, rinse it and the seat clean, check the small pilot holes are clear, and reassemble. If it seals, it is fixed for nothing.

Is it cheaper to replace the diaphragm or the whole valve?

In Perth retail, a complete Hunter PGV 25mm valve at $32.50 to $34.89 is cheaper than a replacement diaphragm on its own at around $50.60. Verified 5 August 2026.