A shed that is located in an area that drains poorly can have problems, including muddy ground or the shed sinking into eroding soil. This can be especially bad if the shed doesn't have a gutter system, and rain water flows directly off the roof and onto the ground. Building a drainage system in the ground near the shed can help remove excess water.
Dig a trench that measures at least 8 inches wide and 8 inches deep that runs from the side of the shed to the area you want to water to drain toward. Slope the soil in the trench at a rate of 1 foot for every 100 feet of run (length). Measure the slope by driving a stake into the ground near the shed and use that as a base. Drive a stake into the ground every 10 feet alongside the trench. Tie a string between the shed post and the first post, and level it out, checking it with a line level. Measure the distance between the string and the bottom of the trench. Tie another string between your first post and the second but one inch lower. Make sure the distance from the string to the trench bottom in this section is the same trench bottom measurement you took from the string tied from the shed post to the first post. Repeat this process down the length of the trench, lowering each string by one inch.
Place 2 inches of gravel into the bottom of the trench. Smooth the gravel with a rake, maintaining the slope at the bottom of the trench.
Cut pieces of 4-inch drain tile drain tile to fit the length of the trench with a hacksaw. Drain tile is perforated pipe used in drainage systems such as this one.
Attach a 90-degree 4-inch PVC elbow to the end of the drain tile that will be in the ground at the top of the trench, and attach a piece of 4-inch PVC pipe to the other end of the elbow. This part of the drainage pipe will extend above the ground with a cap that can be removed so you can unclog the pipe without digging it up.
Place landscaping fabric around the exterior of the drain tile. This helps prevent dirt from clogging the drain tile.
Lay the wrapped drain tile into the trench at the center. Cover the drain tile with gravel until it's about three inches below the surface.