Storm-ready yards: drainage that protects your home.

Southern California gets most of its rain in a few big storms, often after months of dry weather. Dry, hard ground sheds water instead of soaking it in, so a single storm can move a lot of water fast.

• Clay soils. Much of the Temecula Valley and inland North County has expansive clay. It drains slowly, swells when wet and shrinks when dry, which is hard on slabs, walls and foundations.
• Hillside lots. Water from above your property, and from your own slopes, has to go somewhere. Without a plan it goes through the yard and toward the house.
• New tracts. Builders grade a lot to drain on the day of final inspection. Then patios, planters, turf and pavers get added, and the original drainage path is often blocked.
• Older yards. Drains clog with roots and silt, soil builds up against the house over the years, and downspouts end up dumping beside the foundation.

• Water that stands for more than a day after a storm, or a patio that holds puddles.
• Wet soil, mud or a water line against the foundation or the garage.
• White, chalky stains (efflorescence) on block walls, stucco or the bottom of the house.
• Soil that has washed down a slope, gullies on a hillside, or mud on the sidewalk.
• Gutters overflowing, or downspouts that end at the base of the wall.
• Soil or mulch piled up to or over the weep screed, the metal edge at the bottom of the stucco.
• Cracks in a patio or driveway that slope toward the house, or a slab that has settled.
• Drain grates that are buried, cracked or full of debris.

Walk the property during or right after a rain if you can. Where the water actually goes tells you more than any plan.

Grading is the first line of defense. If the ground slopes away from the house, most water never reaches the foundation.

• The building code standard. The California Residential Code calls for the ground to fall at least 6 inches within the first 10 feet away from the foundation. Hard surfaces like patios and walks within 10 feet of the house should slope at least 2 percent away from it.
• When there isn't 10 feet. Side yards are often narrow. The code allows drains or swales to carry the water away instead, which is where area drains and a well-shaped swale come in.
• Swales. A swale is a shallow channel shaped into the ground to guide water along a path, usually down a side yard to the street. It can be lined with rock or planted.
• Keep the original drainage path. When we add patios, walls or planters, we design around the lot's original drainage, or replace it with drains that do the same job.
• Your neighbors. Water shouldn't be redirected onto a neighbor's property. Drainage changes are planned so water leaves your lot the way it is supposed to.

A roof collects a surprising amount of water. Every downspout delivers it to one spot, so where that spot is matters.

• Extensions and splash blocks. The simplest fix: carry water at least a few feet out onto ground that slopes away.
• Downspout adapters into a drain line. An adapter connects the downspout to a solid underground pipe, so roof water travels underground to the street, a swale or a dissipation area.
• Pop-up emitters. The end of an underground line can rise through a pop-up emitter in a lawn or planting bed, well away from the house.
• Solid pipe, not perforated. Downspout lines should be solid pipe. Perforated pipe leaks roof water back into the soil next to the house.
• Rain barrels and capture. Barrels can hold some water for the garden, but they fill fast in a big storm, so they still need an overflow path.

Catch basins and area drains collect surface water in low spots and carry it away through underground pipe.

• Where they go. Low points in a yard, along side yards, at the bottom of slopes, and in the middle of planting areas that collect water.
• Sizing. The grate size and pipe diameter depend on how much area drains to each one. Too small, and they overflow in the first heavy storm.
• Where the water ends up. Usually the street through a curb outlet, or a swale or dissipation area on the property. Never into a sewer cleanout, and never against the foundation.
• When gravity won't work. On low lots where water can't flow to the street or a swale, a sump basin and pump can lift it out. A battery backup keeps it running when storms knock out power.
• Maintenance. Grates clog with leaves and mulch. Check and clear them before the rainy season and after big storms.

A French drain collects water that is already in the soil, not just on the surface.

• When you need one. Soggy ground that stays wet, water seeping through a retaining wall, a high water table near a slope, or groundwater moving toward the house.
• How it is built. A trench with perforated pipe, holes down, wrapped in filter fabric and surrounded by drain rock, sloped steadily to a solid pipe outlet.
• Common mistakes. No filter fabric, so the pipe fills with silt. No slope, so water sits in the pipe. No real outlet, so the drain has nowhere to send the water.
• Clay soil caution. In heavy clay, a French drain that isn't built right can hold water next to the foundation instead of removing it. The rock envelope, fabric and a steady fall to a solid outlet pipe that carries water fully away all matter.
• Not a fix for bad grading. A French drain handles groundwater. Surface water still needs grading, swales and area drains.

Not every drop has to leave the property. Bioretention areas hold water and let it soak in slowly, which helps plants, cuts runoff and fits water-wise landscaping.

• Bioswales. Planted swales that slow water down and let some of it soak in as it moves along.
• Rain gardens. Shallow planted basins that collect water from a downspout or patio and let it soak in over a day or two.
• Placement. Well away from the foundation, typically at least 10 feet, and never on a slope where saturated soil could slide.
• Clay soils. On heavy clay, these areas usually need amended soil or an overflow to a drain, because clay soaks water in slowly.
• Planting. Plants that tolerate both wet winters and dry summers, such as native sedges, rushes and deep-rooted grasses.

Bare slopes are where storms do the most damage. Once soil starts moving, it fills drains, buries patios and can undermine walls.

• Jute netting and erosion blankets. On new or bare slopes, a biodegradable jute net or erosion-control blanket holds soil in place while plants root through it.
• Ground cover and deep roots. Low ground covers protect the surface, and deeper-rooted shrubs hold the slope together underneath. Planting before the rainy season gives roots a head start.
• Riprap. Rock placed at drain outlets, in channels and at the bottom of slopes slows fast water and keeps it from cutting into the soil.
• Brow ditches and terraces. On larger slopes, a lined ditch at the top catches water before it runs down the face.
• Irrigation on slopes. Overwatering a slope is a common cause of slope failure. Drip and low-flow systems on a smart controller help.
• When a slope needs more. A slope that is cracking, bulging or sliding needs a geotechnical engineer, not just plants.

• Keep soil below the weep screed. Soil, mulch and planters piled against stucco hold moisture against the wall and can let water in. Keep the grade below the weep screed and slope it away.
• Planters against the house. Raised planters built against a wall need waterproofing on the wall side and a drain, or they should be moved away from the house.
• Retaining walls. A retaining wall needs drainage behind it: drain rock, a perforated drain at the base, and weep holes or an outlet. The side holding back soil should be waterproofed. Many wall failures are really drainage failures.
• Irrigation near the house. Sprinklers that spray the wall or soak the soil next to the foundation work against good drainage. Drip and careful head placement fix most of it.

• Slope every surface. Patios and walks should fall away from the house so water never sheets toward a door or a wall.
• Channel drains. Long, narrow grated drains at a sliding door, the garage or the low edge of a patio catch water where a surface meets the house.
• Permeable pavers. Pavers with open joints over a deep rock base let water soak through instead of running off. On clay soils they usually need an underdrain.
• Don't block the drainage path. A new patio, wall or turf area laid across a side yard swale is one of the most common causes of yard flooding we see.

Many drainage fixes, like downspout lines, area drains and regrading planting beds, are ordinary landscape work. Some projects need more:

• Grading permits. Moving larger amounts of soil, building up or cutting into slopes, or changing how water leaves the property can require a grading permit. Rules differ by city and county, so we check with yours first.
• Retaining walls. Taller walls, and walls holding back a slope or a driveway, generally need a building permit and engineering.
• Engineers. Large or failing slopes, groundwater problems and drainage that affects neighbors or public drainage call for a civil or geotechnical engineer. We coordinate with licensed engineers when a project needs one.
• HOAs. Many HOAs control slopes, drainage and anything visible from the street, so approval comes before work starts.

1. Site walk. We look at grades, existing drains, downspouts, slopes and where water has been going, ideally right after a rain.
2. Drainage plan. Grades, swales, drains, pipe routes and outlets are drawn into the design, not added later.
3. 3D design. You see the yard in 3D, with the drainage built into the patios, planting and walls instead of fighting them.
4. The build. We build it with the drainage installed first, so everything above it lasts.

• Clean gutters and make sure every downspout is connected.
• Check that downspouts discharge away from the house, not at the wall.
• Clear drain grates, channel drains and curb outlets.
• Run a hose into each drain and confirm the water comes out where it should.
• Pull soil and mulch back below the weep screed.
• Look for low spots where water stood last winter.
• Cover bare slopes with jute netting, an erosion blanket or straw wattles.
• Check that retaining wall weep holes and outlets are open.
• Turn irrigation down or off once the rains start.

Drainage rules and rebate programs change, so check the source before you make final decisions.

• Riverside County Flood Control: Am I in a Floodplain?. Look up your property on the county floodplain map.
• Riverside County Flood Control and Water Conservation District. Regional flood control, drainage planning and storm alerts for western Riverside County.
• SoCal Water$mart residential rebates. Rain barrels, cisterns, turf replacement and irrigation upgrades through participating water agencies.
• San Diego County Waterscape Rebate Program. For unincorporated San Diego County. Projects include stormwater features like rain gardens. Check the page for current status before applying.
• Your city or county building and grading department. For permits on grading, retaining walls and changes to how water leaves the property.

Code references: California Residential Code Section R401.3 and California Building Code Section 1804.4. Getting ready for fire season too? See our fire-safe yards guide.

Send a few photos of your yard and tell us where water collects. You'll get a complimentary concept and budget showing how we would fix the drainage, or call and we'll talk it through.

This guide is general information for homeowners in South Riverside County and North County San Diego. Every property is different, and code requirements vary by city and county. It is not engineering advice.