Splash Block

A splash block is a simple, low-cost drainage accessory — a rectangular pad, typically 18–24 inches long and 12 inches wide, placed under a downspout terminal elbow. It has a sloped surface that directs water away from the foundation and prevents concentrated water discharge from creating a hole or channel in the soil. Most are made from concrete, though plastic versions are lighter and easier to reposition.

Splash blocks are an appropriate solution when the discharge point is at least 4–6 feet from the foundation on relatively level or gently sloped terrain with soil that drains adequately. In Sacramento, however, the clay-heavy soils in most residential neighborhoods create a problem: clay sheds water rather than absorbing it, so even with a splash block, water can pool adjacent to the foundation or run laterally along the soil surface toward the house.

For Sacramento homes on clay soil — which describes the majority of properties in the Sacramento Valley floor — a 4-foot downspout extension, an underground pop-up emitter system, or a French drain connection typically outperforms a splash block as a foundation protection measure. Splash blocks remain useful as a secondary measure at terminal elbows where the primary drainage goes underground, to dissipate the water that backs up through the emitter during peak flow.