Drains can be a little confusing and intimidating. Especially for the average homeowner that does not really know too much about them. A common question that is frequently asked is, what is the difference between a storm drain system and a sanitary drain system? Well, there are actually quite a few differences between a storm drain system and a sanitary drain system. There are things like the location of the systems, where the water comes from, and processes they go through. But a simple way to explain and describe their differences is as follows.
A sanitary drain system is designed to take the discharge water (which is just contaminated water), from equipment in your home that generates water, to get treatment that would make it clean. The drain system basically carries contaminated water that needs to receive treatment. Whereas the storm drain system is used for water that comes from the ground and weather conditions. This water is not contaminated by human waste.
Some examples of these differences are that, the sanitary drain would be taking water from bathrooms, sinks, and toilets in your home, and proceed to drain that contaminated water in a line to receive treatment. However, the storm drain system would take ground water from rain or snow that has melted, and drain it in a separate line. It is not contaminated so it does not need the treatment that the sanitary drain system needs.
However, in a city, sometimes there is a combined system. What is a combined system you might ask? A combined system is just like what the name “combined system” suggests. It is when the ground water is mixed with the drained water from the houses. Or in other words, it is when the storm and sanitary drain systems are mixed together.
So, when a plumber arrives, they can quickly figure out what type of system they are dealing with, whether it is a sanitary drain system, storm drain system, or combined drain system. Then, they can tell you the next steps that are needed to effectively fix the problem with that specific drain.
Right now, the code requirement is that the storm system cannot be mixed with the sanitary system. This is because even though the sanitary drain is contaminated by human waste, the storm system is uncontaminated and does not need the treatment to clean it. They need to be apart so that the uncontaminated water does not have to go through the cleaning treatment, and the contaminated water gets all the treatment it needs.
Now that it has been broken down, the difference between storm drain systems and sanitary drain systems should be a lot clearer. Clearly, there are some big differences between the two. Starting from where the water comes from, to what happens to them afterward.