Could Your Reverse Osmosis System Be Doubling Your Water Bill?
A sudden spike in your Canal Gestión bill is one of the most common reasons people contact us. The assumption is usually a burst pipe or a pool leak, and sometimes that is exactly what it is. But there is another cause that catches villa owners off guard, and it leaves no puddle, no damp patch, and no obvious sign of anything wrong.
The reverse osmosis system under your kitchen sink.
Many properties across Lanzarote are fitted with under-sink RO filtration units. The island's mains water is desalinated and perfectly safe to drink, but the taste puts a lot of people off, so RO systems are common. What most owners do not realise is that a faulty unit can run water to drain continuously, 24 hours a day, without ever giving you a visible clue that anything is wrong.
How the System Works — and How It Fails
A reverse osmosis unit pushes water through a membrane to filter it, producing clean drinking water on one side and a brine or wastewater stream on the other. The wastewater goes directly into your drainage system. When the storage tank is full, an automatic shut-off valve is supposed to stop the process.
When that valve fails — and they do fail, particularly in older units — the system keeps running. Water keeps flowing through the membrane and straight down the drain. Because it exits through your waste pipes rather than appearing anywhere in the property, there is nothing to see. The only evidence is on your water meter.
Three Signs Your RO Unit May Be Running Non-Stop
There are a few checks you can do yourself before calling anyone out.
1. Sound
Open the cupboard under your kitchen sink when the tank should be full — typically first thing in the morning before anyone has used the tap. A healthy system should be silent. A faint but constant hissing or trickling sound suggests water is still moving through the system when it should not be.
2. Temperature
The small plastic drain line that carries wastewater away from the unit should only be cold when the system is actively filtering. If it feels cold to the touch at any time of day, water is flowing through it continuously.
3. The Meter
Go to your water meter when every tap, appliance, and irrigation system in the property is off. Watch the dial for two minutes. Any movement at all indicates water is being consumed somewhere. An RO fault will typically show as a slow, steady rotation rather than the intermittent movement you might see from a dripping tap.
The Isolation Test
If you suspect the RO system, there is a simple way to confirm it before spending money on a full survey. Locate the dedicated cold water feed valve that supplies the unit — it is usually a small quarter-turn valve on the cold supply pipe inside the cupboard — and turn it off. Wait twenty minutes, then check the meter again. If the dial has stopped moving, the RO system was the source of the consumption. If it is still moving, the leak is elsewhere in the plumbing and you need professional help to find it.
When to Call the Professionals
If the isolation test points to the RO system, the fix is usually straightforward — a replacement shut-off valve or a new unit entirely. If the meter is still moving after isolating the RO system, the problem is underground or concealed within the structure, and that requires specialist detection equipment to locate without causing unnecessary damage.
We offer a free leak confirmation test as a starting point. We check your meter, ask the right questions, and tell you honestly whether you need a full survey or whether the problem is something you can resolve yourself. Our No Find, No Fee guarantee means you only pay if we locate the leak.
Contact us today and find out exactly where your water is going.