For those that recall, our home has a number of rain barrels around it. Well, the ones we installed last year were great - until we had a massive intense rain event on our small urban lot. There were a series of issues that combined to cause some water to enter our basement:
- Lots of rain - a few inches in a half hour
- Lots of water hitting two rain barrels
- Rain barrel overflow hose way too small to accommodate flow
- Barrels located near our exterior basement stairs
- Neighbor's downspouts also directed towards this area
- Concrete step that was disintegrated, allowing water to head downhill
- Floor drain full of leaves and debris, preventing drainage
= Water coming in the house under basement exterior door!
- Gutter diverter
- Rain barrel interconnection
- Underground discharge
- Wider overflow hose
2. Rain barrel interconnection. Every set of directions I've ever seen for connecting rain barrels seems to say they should be interconnected at the top overflow hose. After our basement flooded, I thought about this and it makes no sense. If you connect two or more barrels at the bottom, they will fill up at equal rates rather than having one fill up completely and hoping the overflow works faster than any new rainwater coming in. Here's a photo showing the diversion system, as well as the two barrels (on either side of our side gate) connected in tandem. The connection hose is hidden from view behind them.
3. Underground discharge. I know I'm a nerd when I think this was a fun way to spend some time. When excavating for our bluestone pavers last year, I had the foresight to take advantage of the opportunity to dig a bit deeper, and create an overflow area for storm water that would carry it away from our our home's foundation wall. I purchased a 10' section of 4" PVC, added an elbow and a cleanout with a cap on one end (which can be capped in winter), and a Tee with access port on the other end.
After this, I connected 10 feet of drain tile (perforated tube) wrapped in landscape fabric to prevent silt infiltration, and ran it out where the old concrete sidewalk had been. All told, this runs about 25 feet away from the foundation wall.
Honestly I recognize this is excessive to accommodate overflow and way more than what most people need. Don't be scared into thinking you have to do this if you want rain barrels. We did this more because we had the opportunity. That said, you do need to have some kind of plan to take the overflow from the barrels. I highly recommend the following video showing more traditional rain barrel overflow.
4. Wider overflow hose. This particular downspout handles exactly one-half of the roof area of our home, over 1,000 square feet of surface area. In a 1" rainfall, that means we're getting 620 gallons of water! Because of the large roof area, our (2) 65-gallon rain barrels fill up after roughly 1/4 of an inch of rainfall. In heavier rains, the small garden hose overflow can not handle the volume of water coming down the downspout.
The solution? Drill a new hole and install a 1.5-inch wide sump-pump hose. If its' good enough for leaky basements, its good enough for several gallons of rain per minute. Sump-pump hoses are sold in 20' lengths. I tried searching for something shorter but then I realized that I could snake the entire 20 feet all the way through the 4" drain tile system mentioned above. This puts the overflow way out in the yard in case there wasn't enough pitch to carry the water away. For you eagle-eyed home improvement experts, the hose is connected to an old stainless steel drain fitting from one of the sinks we took out of the home.
So, with these four measures, our stormwater management system is much better engineered. As I mentioned earlier, this type of system is overkill for most homeowner's needs. But we had a confluence of events that led to a leaking basement, and we don't want to have that ever again.
The weather the last few weeks in Chicago has put this to the test as it has been raining almost every day. Our barrels are full, and the manual downspout diverter is sending excess water to the storm sewer system. And I can sleep better knowing that any water that splashes past the diverter and makes its way to the rain barrels is overflowing into the backyard, away from the basement.