It's true that RO purifiers reject some water as waste by design — that's how the membrane filters out dissolved solids. But if your purifier seems to be wasting far more water than it's producing, that's usually not normal operation; it's a fixable fault.
Normal vs Excessive Waste
Most home RO systems run at roughly a 1:2 to 1:3 ratio of purified to waste water, depending on membrane type and input water pressure. If your ratio looks dramatically worse than that, or the unit drips continuously even when the storage tank is full, something needs attention.
Common Causes
- Faulty solenoid valve — this valve is meant to stop water flow once the tank is full; if it's stuck or worn, water keeps flowing to waste continuously
- Worn check valve — allows water to flow backward through the system, increasing waste
- Choked or ageing membrane — as membranes age, they can reject more water than they used to for the same purified output
- Low input water pressure — forces the system to work harder and waste more to achieve the same purification
What We Check
On a service visit, we check the solenoid valve function, check valve condition, membrane performance (via a TDS/output test), and input pressure — all quick checks that usually identify the cause within the same visit.
If your purifier's waste output has visibly increased, it's worth a service call before it turns into a bigger repair — worn valves are inexpensive to replace, but a neglected membrane eventually needs full replacement.
