What’s the Difference Between a Drain & Sewer?

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Drain? Sewer? These words, though quite different in meaning, seem to be used interchangeably by some. This is unfortunate as many refer to a sewer when they really mean ‘drain’ and refer to a drain when they mean ‘sewer’.

So, what is the actual difference between the two? Is it really a matter of appearance or it is more to do with function? The answer is a little bit of both.

What Is a Drain?

By definition, a drain is a pipe that serves only one building, anything from a house to an office block. All water and wastewater is carried along this pipe into the sewer system.

There are all kinds of drains, all of them serving a different purpose. A lateral drain, for instance, is a section of drain positioned outside the boundary of any particular building which can connect it with drains in other nearby buildings to become a sewer.

A drainage system can be either natural or artificial, but the main purpose is to deposit any wastewater into a nearby reservoir or the sea.

What Is a Sewer?

Sewers (or sewerage system) are an underground network of pipes that hold sewage (which is normally wastewater mixed with human waste), wastewater and water run-off from drains and directly into waste treatment plants or disposal points.

All drains lead to sewers and all sewers lead to a treatment plant in some form or other, never directly into a natural reservoir or other body of water.

Sewers are always artificial, too, as nature does not tend to produce such a complex network of pipes or any way of disposing of such waste properly.

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