cost per linear foot for french drain
1 French drains cost approximately $20 to $30 per linear foot. 2  A reasonable estimate to do a home is $1,000 to $2,00 0 but could be more depending on the size and soil conditions.3  Because a lot of foundation flooding is due to improper water runoff, a cheap solution could be to install new downspout drainage. French drains cost approximately $20 to $30 per linear foot. 2  A reasonable estimate to do a home is $1,000 to $2,00 0 but could be more depending on the size and soil conditions. 3  Because a lot of foundation flooding is due to improper water runoff, a cheap solution could be to install new downspout drainage.