[emighty]

A foul smell like the smell of sewage comes from some of my drains whenever it rains.

[thommyschnak]

That can be a serious health issue, sewer gas can prove to be lethal, as well as extremely unsanitary. I would definiatly make sure that you have the required drain traps, and that you make sure that there is always water in the traps. If your drain traps dry up you will smell sewer gas in the his-ous.

[ballengerb1]

Check your vent stack, it may be partially blocked and this can back up sewer gas and/or siphon water from the traps. Rod the vent from the roof with a rented sewer rodder. Use enough snake to reach roof to basment floor plus 20'.