as you can tell by now, I got a long list of renovation projects OK here's the deal. We have a basement built with cement block units, those textured ones. Obviously the basement leaks, the previous owner 50 years in the house apparently dug the flow under the footer (!) to make more head space and now that's where the water leaks in. I want to dig around the foundation and install a drain. Will the foundation get damaged if I do so? Will it actually help since the floor is about 6" too low? My understanding is the floor has to be poured 4" above top of footer. Alternative options have been mentioned to me: dig inside and put the drain inside. Don't like that idea, also don't like the idea of sump pumps. When you create a repeated path for water to flow, wouldn't it wash out the soil after a while? I think those systems actually make it easier for water to enter the house. Right now I put new gutters on that drain to the street and sloped the ground. Also installed a surface trench to get storm water to flow away from the house. I poured a 1 ft high hydraulic cement bar around the interior on top of the footer and it works well. Problem: when it rains more than 4"/24h the water level rises over the hydraulic cement and into the basement. Any ideas on how to excavate? We have clay soil here

Can you install an exterior drain line to daylight? If so, the best route is exterior - all you have to watch out for is the house falling over by excavating below the footing. you can do that by pouring sections of footings as you go, but it's a job for a professional.

the interior route works pretty well - you line the trench with filter fabric, washed stone & filter fabric so it won't wash out, then excavate an exterior route to daylight and connect it with a pipe under the footing. Again, you'll need to be very careful not to undermine the house so getting in someone who has done this would be a good idea.

Hi Bob thanks for the info!

My concern is if I install a drain so close to the footer, whether inside or outside but I believe the interior is more risky, wouldn't it wash out the soil under footer in the long term?
I mean water takes soil particles with it and eventually washes it out, doesn't it?
In my case water comes from under the footer into the house because the floor was dug down too low, down to the bottom of the footer (the entire footer is visible from inside)....

I was thinking the footer drain strategy may be less of a risk when the drain is installed above the footer, but below the footer.... I don't know!?