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Storm vs. Sanitary Drain Systems

Marcin from ExpressRooter, the official contractor for Mike Holmes, is here to address some of the common questions that many homeowners ask.

Storm vs. Sanitary Drain Systems

A question that home owners often ask is, what is the difference between the storm and sanitary drain system? The sanitary drain system is designed to take discharge water from all the fixtures in a house, bathrooms, kitchen sink, toilets, and discharge or drain that water for treatment. Storm systems are designed for ground water, rain water, or water that is not contaminated by human waste. That water is exterior water that comes from the rain, melting snow, or weeping tile systems that pick up the ground water; draining it in a separate line designated as a storm system.

In a city there is sometimes what is called a combined system; the line that takes the ground water is mixed with the water that is discharged from the house. When the plumber arrives at a location, they will be able to quickly diagnose what type of system they are dealing with, the difference between the storm and sanitary drains or combined system, and be able to advise you on what would be the necessary steps to resolving any issues that you are having in your home. By current code requirement, the storm system has to be independent of the sanitary system, isolating the ground rain water as this water is not contaminated and there is no need for treatment. Only the sanitary line has to be treated and therefore has to be independent and kept in a separate line.

If you have any questions with regards to storm systems or sanitary systems, please call our office at 416-233-2660 or visit our website at

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