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Where Should Downspouts Drain on a Las Vegas Home?

Written October 8, 2026. Code and statute text was read the same day.

Key Takeaways:
Five feet is the number. Where expansive or collapsible soils are known to exist, the residential code Clark County lists as adopted for 2026 calls for roof water to be discharged at least 5 feet from the foundation walls or into an approved drainage system.
Away from your house and away from the neighbor's. That is the test in Southern Nevada's plumbing code amendment for where a house may send storm water.
Nevada's water law does not apply to small-scale rain collection from the roof of a single-family home for nonpotable household use. That is NRS 533.027, added in 2017.
You can test every downspout on a dry day with a garden hose and a bucket.
None of this is legal advice. Confirm what applies at your address with your building department.

Where should a downspout drain on a Las Vegas home?

At least 5 feet from the foundation, onto ground or concrete that slopes away from the house, and never toward the lot next door. A gutter does not get rid of roof water. It gathers the whole roof and delivers it to a handful of points on the ground, so each point has to be right.

The U.S. Geological Survey figures one inch of rain on a 40-by-70-foot roof at about 1,743 gallons. Now picture one downspout that drains 600 square feet of roof in a half-inch storm. If all of that water lands on a patch of ground 2 feet by 2 feet beside the slab, the patch takes as much water as 75 inches of rain falling straight on it. A normal year in Las Vegas brings 4.18 inches, by the National Weather Service. That patch just took about 18 years of rain in one storm.

That is why our downspouts and drainage page says a downspout dumping at the base of the foundation wall is worse than no gutter at all.

What does the building code in Southern Nevada say about roof water?

It says to get roof water at least 5 feet from the foundation where problem soils are known to exist. The section is R801.3 of the 2024 International Residential Code, titled Roof Drainage: "In areas where expansive soils or collapsible soils are known to exist, all dwellings and townhouses shall have a controlled method of water disposal from roofs that will collect and discharge roof drainage to the ground surface not less than 5 feet (1524 mm) from foundation walls or to an approved drainage system."

Clark County's building department lists the 2024 residential code as adopted, effective January 11, 2026, and the City of Las Vegas lists it with an effective date of January 2026. As Clark County posts them, the Southern Nevada amendments to the residential code list no change to R801.3. They do rewrite the lot drainage section, R401.3, which covers the ground the downspout lands on:

WhereWhat amended R401.3 says
Ground next to the houseSlope away from the building at 5 percent for at least 10 feet, which is 6 inches of fall
Low expansive, low collapsible, low soluble soil, or asphalt or concrete at the wallThe slope may be reduced to 2 percent
Concrete and other hard surfaces within 10 feetAt least 2 percent away from the building, about a quarter inch per foot
Lot line closer than 10 feetThe 5 percent slope runs to an approved alternative way of diverting water, such as a swale

Two cautions. These sections govern how a house is built and permitted, and none of this is legal advice. The amendments also say they "are not code unless adopted and codified by governmental jurisdictions." Confirm what applies at your address with your own building department, and read your HOA's rules before you change anything visible from the street.

Why do Las Vegas valley soils make this matter?

Because the local building rules treat soil that swells, settles or dissolves when wet as a condition to plan for here. Clark County's building department keeps three soils maps, among them the Clark County Expansive Soils Guidelines Map, and describes them as "a tool to show historical trends of near-surface soils in the Las Vegas valley area."

The Southern Nevada amendments to the building code require a soils report to address "collapsible soils, expansive soils (swell), soluble soils, corrosive soils" and, as a separate item, caliche and cemented soils. In plain words:

  • Expansive soil is clay that swells. The Nevada Bureau of Mines and Geology puts it this way: "Some clays such as montmorillonite swell when wet and can cause structural damage to buildings with improper foundations."
  • Collapsible soil is dry, loose ground that settles when water reaches it. The U.S. Geological Survey calls the process hydrocompaction, "compaction due to wetting."

The ground also changes across town. The USGS describes the valley as a trough filled with gravel, sand, silt and clay, coarse around the rim and finer toward the central and eastern part. For a concern about swelling soil, the Bureau says to "check with the local county or city engineer or hire a consulting geologist or engineering firm."

We install gutters and do not test soil, so nothing here is a reading of the ground under your house. With soil that swells and soil that collapses, the trouble starts when water reaches it, and a downspout pours water on the same small patch storm after storm.

Can a downspout drain toward the neighbor's lot or across the sidewalk?

Not toward the neighbor. Southern Nevada's amendment to plumbing code section 1101.2 says that for one- and two-family dwellings, "storm water shall be permitted to be discharged on flat areas, such as streets or lawns, so long as the storm water shall flow away from the building and away from adjoining property, and shall not create a nuisance."

The amendment has one exception, for townhouses and two-family dwellings whose storm water goes onto ground kept up by a common interest community under approved CC&Rs. This is not legal advice. Confirm with your building department.

The street is named in that sentence, and from many front yards the way to the street crosses the sidewalk. The test the rule gives is nuisance. One hard stream across a public walk leaves silt and a slick spot. Spread the water on your own ground first, send it down the driveway, or carry it under the walk in a drain.

Two city ordinances speak to water on a sidewalk. Las Vegas Municipal Code 13.04.030 and Henderson Municipal Code 11.05.040 each make it unlawful for a person who owns or controls "any hose, water pipe, ditch, canal, flume, lawn sprinkling system or waterway" to let water from it "or from any other source" flow "over or into any sidewalk, street, alley or public place." Neither one mentions rain or roofs. For how your city reads it, ask the city.

The same plumbing amendments list rain water as a prohibited discharge to the building sewer, and they leave the details to the local authority. A downspout does not go into a sewer cleanout. Confirm with your building department.

Are rain barrels legal in Nevada?

At a single-family home, the state's water law does not stand in the way. Chapter 533 of the Nevada Revised Statutes, the state's water law, says its provisions do not apply to the "de minimus collection of precipitation" from "the rooftop of a single-family dwelling for nonpotable domestic use." That is NRS 533.027, and its history note shows it was added in 2017. The statute does not speak to city or HOA rules, so check those before you set a barrel. This is not legal advice.

The barrel is the small part of the job. By the USGS figure, a quarter inch of rain on 1,000 square feet of roof is about 156 gallons, and a 55-gallon barrel under that downspout is full after less than a tenth of an inch. The rest leaves by the overflow, so pipe the overflow at least 5 feet from the foundation like any downspout. Keep the lid screened. Standing water breeds mosquitoes, and the Southern Nevada Health District monitors standing water sources. An HOA can have its own rules about where a barrel sits, so check yours first.

How do I get the water 5 feet from the slab?

With the simplest thing that works on that side of the house. From least work to most:

  • Concrete that already drains. A driveway or walk that falls toward the street is the best landing a downspout can have. A level will tell you if it has the quarter inch per foot.
  • A splash block. It breaks the fall and keeps the outlet from digging a hole. It is short, so by itself it does not carry water 5 feet out. It only works where the ground past it slopes away.
  • An extension. A length of downspout laid along the ground from the elbow to the 5-foot mark or past it.
  • An underground drain. Solid pipe from the downspout to a pop-up outlet in the yard or to the curb. It needs fall along its whole length, a cleanout you can reach and an outlet you can see. A blocked drain sends water back to the wall where nobody notices. Ask your city or county public works office before anyone cuts a curb.

The one place we never send a downspout is a planter or a walled bed against the stucco. A raised bed holds water at the wall, which is the opposite of the slope the code asks for.

Sometimes the fix is at the top. We move downspouts when the original spot sends water against a walkway, pools it at a garage foundation, or drains it into a bed that cannot take the volume. We also add downspouts to existing gutters. If a gutter spills before the water ever reaches the downspout, that is a different problem, covered in why gutters overflow in heavy rain.

Does desert rock landscaping take care of the water?

No. Rock covers the grade. It does not change it. Water drops through the rock and follows the soil underneath, so a rock bed that tilts toward the house delivers water to the house. Plastic sheeting under the rock carries the water to its low edge.

What rock does well is take the hit. Fist-size rock at an outlet stops the splash and the trench, where small gravel washes out.

How do I test my downspouts with a garden hose?

Run water at each downspout's outlet on a dry day and watch where it goes. You do not need a ladder.

  1. Time your hose filling a 5-gallon bucket. One minute to fill means 5 gallons a minute.
  2. Lay the hose where the downspout lets out and run it for 10 minutes.
  3. Follow the water. It should move away from the wall and keep going. Note any spot within 10 feet of the slab where it ponds or turns back toward the house, and whether it heads for the neighbor's wall.
  4. For an underground drain, put the hose in the inlet and go find the outlet. If the inlet backs up, the pipe is blocked.
  5. Come back in an hour. Water still standing near the slab is the thing to write down.

Then scale it up, because a hose is gentle. NOAA's rainfall atlas puts a 15-minute burst that comes about once in 10 years in downtown Las Vegas at a rate of 2.08 inches per hour. At that rate a downspout draining 600 square feet of roof carries about 13 gallons a minute. A puddle at 5 gallons a minute is a pond in a storm. Our 2026 monsoon recap shows how fast rain arrived here this year.

Do I need a gutter company for this?

Often not. A splash block or an extension is a hardware store errand. Call a gutter company when the downspout is in the wrong place, when one outlet carries too much roof, or when the gutter above it overflows. Call an engineer, not us, for cracks or movement in the slab or the walls.

Frequently asked questions

How far from the foundation should a downspout discharge in Las Vegas?

At least 5 feet. Section R801.3 of the 2024 International Residential Code, which Clark County lists as adopted, calls for roof water to be discharged not less than 5 feet from foundation walls or into an approved drainage system where expansive or collapsible soils are known to exist. Confirm what applies at your address with your building department.

Are rain barrels legal in Nevada?

At a single-family home, the state water law steps aside. NRS 533.027, added in 2017, exempts the de minimus collection of precipitation from the rooftop of a single-family dwelling for nonpotable domestic use. Not legal advice; check your city and your HOA.

Can a downspout drain toward my neighbor's yard?

Not at a single-family house. Southern Nevada's amendment to the plumbing code lets a house discharge storm water onto flat areas such as streets or lawns only so long as it flows away from the building and away from adjoining property and does not create a nuisance. Not legal advice; confirm with your building department, because the amendment has an exception for townhouses and two-family dwellings in a common interest community.

Can I run a downspout into the sewer cleanout?

No. The Southern Nevada amendments to the 2024 Uniform Plumbing Code list rain, surface or subsurface water as a prohibited discharge to the building sewer. Not legal advice; confirm with your building department.

Is a splash block enough?

Only where the ground past it slopes away from the house. A splash block is short, so by itself it does not carry water 5 feet from the foundation.

Does City Seamless move or add downspouts on existing gutters?

Yes. We relocate downspouts when the original spot sends water against a walkway or a foundation, and we add downspouts to existing gutter systems.

Related City Seamless resources

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About City Seamless Rain Gutter

Company: City Seamless Rain Gutter, family-owned in Las Vegas, with trade roots dating to 1976
Nevada Contractor Licenses: #0081882 and #0082656
Awards: Best of Las Vegas, Las Vegas Review-Journal, 2024 and 2025
Installations: 30,000+ homes installed
Standard Material: .032-gauge aluminum
Warranty: 30-year material warranty and a 5-year workmanship guarantee
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