What happens if rainwater is allowed to enter "the stack" ?

[Amilcar]

What does the building term, "rainwater should not discharge into the stack" mean and what would happen if this were allowed to happen? What, indeed, is, "the stack" ?( I am trying to understand some conditions imposed in Building Regs.) Any lght thrown would be appreciated. Thanks.

[jackthehat]

Surface (rainwater) must be kept to a separate system from the foul water (sewage) system..........unless your house has a combined system - this is common in older properties.

[jon1968]

The stack is the big fat pipe that your sewerage goes into, it’ll be open at the top to vent. Basically, it means you can’t run your guttering into the same pipe your toilet waste is connected to.

“what would happen if this were allowed to happen” If one person does it then not much, but if everyone in your street did it then your sewers couldn’t cope, the throw of water off of even a small roof is phenomenal.

[scotman]

As above, 'the stack' is one of the names for the pipe that takes the soil(sewage) away. If run-off water goes into this as well then the sewage treatment works can have difficulty dealing with the volume and untreated sewage may be released.