Drainage Failures in Carlsbad, Encinitas, and Solana Beach
What to Fix Before the First Rain
Homeowners who call us about drainage in October are asking the same question: my yard got through last winter, so will it get through this one?This year that question has a sharper edge due to concerns about El Niño. As most San Diegans know, there is an El Niño Advisory in place, and we have a better than 90 percent chance of a very strong event through fall and winter 2026–27, and a 75 percent chance of an event stronger than any on record back to 1950. Nobody can tell you what will land on your lot. But a system that only just worked in an average year isn't a great bet.
We get called to repair drainage just as much as we do to design it. The failures cluster in five places.
1. The Grade, Not the Pipe
In almost every yard where we are asked to "add drainage," the issue is actually a grading problem, not necessarily a plumbing issue. No pipe network compensates for a yard that falls toward the house.The California Residential Code sets the floor. The grade is required to fall no fewer than 6 inches within the first 10 feet from the foundation - about 5 percent - and impervious surfaces within that same 10 feet must slope away at not less than 2 percent. Where lot lines, walls, or slopes make that impossible, the code's own exception is explicit: build drains or swales instead, and a swale in that zone still carries a 2 percent minimum.
That exception describes most of our lots. On the narrow side yards common in older Encinitas and Solana Beach neighborhoods, there is no room to fall 6 inches in 10 feet without ending up below the neighbor's grade. The swale becomes the primary system, so its slope and its outlet get engineered rather than eyeballed. A swale that looks right and falls at half a percent will stand water against your stem wall every time a storm outruns it.
2. Pipe Sized by Habit instead of Contributing Area
Four-inch pipe is the residential default because it is what is on the truck. The plumbing code does not work that way. California Plumbing Code sizes storm piping off the horizontally projected roof and paved area feeding it, and diameter and slope are paired. They are one decision, not two. The hardscape half of that area is what gets forgotten: a 900-square-foot paver patio and a new driveway apron count exactly as much as the roof.Then there is the fall you have to spend. A 1 percent line is 12 inches of drop across 100 feet. On a flat lot, 12 inches is often the entire vertical budget between the back of the house and the only legal outlet - which is why the answer there is frequently two shorter independent runs instead of one long collector.
3. Inlets on a Grid Instead of at Low Points
Catch basins get spaced evenly because an even grid draws nicely on a plan. Water does not read plans. Inlets belong where water collects - the bottom of the swale, the gate pinch point, the base of the step run, upslope of the patio edge.A sump below the outlet. A basin with its pipe at the bottom of the box is a tee with a lid. Four to 6 inches of sump below the outlet invert catches silt and lets you shovel it out. After a dry San Diego summer, the first real storm carries a remarkable load of fines, and everything downstream of an unsumped basin collects them.
Access. A cleanout is required at the base of each leader or conductor before it ties into the horizontal drain. What closes grates here is specific: coast live oak, Brisbane box, and eucalyptus litter, dropping on a schedule that lines up with the first storms.
4. Daylight, Pump, or Drywell
A drainage system is only as good as where it ends.Daylight is the first choice every time: a gravity outlet lower than every inlet, discharging where the water does not become someone else's problem. Storm water should never go into the sanitary sewer, and the outfall gets identified before the trench is dug.
A pump is the fallback when the fall does not exist. We install them where they are the only option, and say so plainly: a pump is a mechanical part and a power dependency in the exact storm you need it for.
A drywell only works if the soil takes water. On the heavier soils common inland in Vista and parts of Rancho Santa Fe, 0.025 inches per hour is effectively no infiltration. A drywell cut into that soil 10 feet off the house is not a drainage solution; it is a reservoir held against your footing. We percolation-test first, and on a fair number of lots the test is what kills the drywell.
5. French Drains Installed for the Wrong Problem
French drains are the most-requested and most-misapplied item in residential drainage. They intercept subsurface water. They are slow at surface water, which is usually what the homeowner is fighting.Where one is right, the build matters. Subsoil drains must be at least 3 inches in diameter, laid in gravel, slag, or crushed rock with no less than 4 inches of that material surrounding the pipe. The failure we find is never the pipe. It is a sock-wrapped perforated line bedded in native silty soil with a token handful of rock, which blinds off within two seasons and convinces the homeowner that drainage "doesn't work." We use clean washed rock, sourced through KRC Rock in San Marcos, in a volume that does the filtering, and match the fabric to the soil.
Where to Start
If water stood anywhere on your property last winter, now is the time to address it: identify the outlet, confirm the fall you have, and test the soil before anyone specifies a pipe size.Because we design and build in-house, the person who sets the grades installs the system and answers for it in February. To have your drainage looked at before winter, contact Afuera Landscape Designs for a design consultation.
