Smoke generator used in the testing, Source: Valmiera Municipality

Valmiera smokes water irregularities out – literally

Valmiera smokes water irregularities out – literally

The method is employed to make sure that sewers and rainwater drains stay separate

Valmiera’s official portal reported this week on the results of an interesting test campaign that has been evolving since January – using a smoke method to find out if rainwaters are being discharged into the sewers in residential homes. The initial campaign in the Latvian town showed that out of 386 inspected properties, 45 had such infractions, in other words, every 8th house.

The operation was carried out by the local water supply company Valmieras ūdens, and the owners whose water drainage systems were found to be irregular have been duly notified with a notice to rectify the situation.

Why is mixing rainwater and domestic use water problematic anyway?

Some readers might wonder what the big deal is to discharge rainwater in the city sewer system, and yet others might even be surprised that the two flows are managed by different pipe networks and do not end up in the same place.

The difference is that rainwater comes from nature and is meant to return there without treatments, meaning it is led back to streams and rivers. Water that has been used for domestic purposes is often contaminated with impurities after operations, such as cleaning and consequently goes through treatment stations. Adding rainwater to the sewers poses the risk of overburdening them and consequently causing them to overflow and create floods on the streets – that is why the two are kept separate.

The way the test itself worked was by placing a smoke generator inside the pipes and see where it comes out of the drains. The officials assured that the smoke itself was harmless to the environment and humans.

The property owners where the infractions have been detected will have to take steps to disconnect the rainwater drains from the centralized sewer system. If it is not considered possible the water supply company has said that owners can request paid services for rainwater drainage and treatment.



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