To keep your basement dry, the first thing you need to do is control rainwater runoff. The most common source of rainwater is the water which comes from our roofs. This water can come in very large volumes and create a massive flow of water around your foundation. A two-inch rain is equal to almost 2,000 gallons of water from a 30' X 50' residential roof. If this 2,000 gallons of water is not directed away from your foundation, it can cause cracking and flooding inside the home.
Directing your downspouts directly into a drain pipe is a fairly common and simple solution to controlling rainwater runoff. This is as simple as digging a trench and laying a solid drain pipe inside this trench and directing it at least 10’ away from the foundation. The outlet can be a simple emitter, drain grate or, if an adequate slope is available, daylighting. This type of system is very common and, with proper pitch and size, it can be very efficient. The downsides to a direct connection system are clogging or freezing.
Another very effective method of controlling downspout discharge is the use of a catch basin. The catch basin is placed directly below the downspout outlet and serves as a collection point which transfers the water to a solid drain pipe and then to an emitter or grate. The distinct advantage of the catch basin is the grate, which covers the top of the unit. This grating serves as a filter to prevent debris from clogging your underground pipe. Simply wiping off the grate periodically will keep the system working efficiently.
The other benefit of a catch basin is its ability to collect pooling surface water. If your soil is not adequately sloped away from the foundation, the catch basin can collect some of this surface water and drain it away just as it does with the rainwater from the roof.
Catch basins come in a variety of sizes and outlet configuration which should be taken into consideration when designing your system. Basin selection will be a function of anticipated water volume, piping size, and depth and water source layout. This is best done by a water management expert or landscape architect/engineer. Next is the fun part - grate selection. Catch basin grate selection is very broad to the point that you can pick the color, style, and material based on the aesthetics and volume required. Plastic, green and black being the most common, is the most economical. Brass, copper, or chrome would be a more personal statement that can add to the overall landscape design, but more expensive.
Whichever method you choose, direct connection to a solid drain pipe or the catch basin design, the key is to collect stormwater runoff and direct it away from the foundation. Remember, the goal is to protect your home from flooding and foundation damage.