Not Replacing the Filter on Time
The most common mistake Indian households make with a water purifier is treating the filter like a permanent fixture. RO and UV filters have a fixed lifespan, typically 6 to 12 months depending on usage and source water quality, after which they stop removing contaminants effectively and can begin releasing trapped bacteria back into the water. A 2019 study published in the journal Environmental Science and Pollution Research tested household RO units in Delhi and found that overdue filters in 38% of sampled homes were delivering water with coliform counts above WHO safe limits. The filter indicator light, when it exists, is not decorative. When it turns red, the filter is already past its effective window.
