We parallel our downspouts inside our French drain system as its own line, but never put that water directly into the drain system. Here we are running dual 4” pipes side by side with a 4” pvc downspout pipe next to those. The system is filtered by 4oz non-woven geotextile fabric and wrapped like a burrito. On top of the pipes will be 1-1/2” river rock. Smooth, round rock has more void space for air and water than angular rock. The trench is flat, but pitches about 1/4” per foot. We put the pipe

10 Things I Learned Installing a French Drain

Salt in the Bathroom Drain, and Sink Will Surprise You with Many Benefits For Your Home !