Plumbing Building code in California (CA): IMPORTANT rules and laws to pass the inspection

If you install a plumbing system, it is essential that you know the local plumbing and building code. An inspector might reject your installation and it is possible that you have to rip everything out. This can be very expensive and cost a lot of time.

Using the right types of materials in the correct place is very important if you want to get your home plumbing installation approved. An inspector will check your installation to make sure that everything is up to code. The code changes every 3 years. 

Sometimes older systems are grandfathered in. For newer installations, there are no exceptions. The goal is to make sure that the house is safe for the inhabitants, nature, and the neighborhood.

Plumbing deals with hot water, electricity, gas, exhaust, and wastewater. Each of these can be dangerous if they are not properly handled. For this reason, plumbing codes are essential and have been used for several decades. They have greatly reduced the number of accidents and the amount of damage. 

Plumbing code laws in California (including Los Angeles, San Francisco, San Diego, San Jose and Long Beach)

Small details (such as the width of a pipe or how it is supported) can be important so it is essential that you check them before you start installing a system.

The plumbing code in California has the following important sections for homeowners:

  • Plumbing fixtures and fittings
  • Water heaters
  • Water supply and distribution
  • Sanitary drainage
  • Indirect waste
  • Vents
  • Traps and interceptors
  • Storm drainage
  • Firestop protection
  • Alternate water sources for nonpotable applications
  • Nonpotable rainwater catchment systems

Let’s go over each of these to discuss some important points. For all the details, you should check the plumbing code itself.

Plumbing fixtures and fittings

A lot of this comes down to buying the right material. Go to a local hardware store that has the items that are allowed in California. 

The pipes have to be marked to indicate the quality and type of material. Pipes have to be insulated if they are in cold areas (such as attics or outside).

Water pipes need proper support so that they don’t sag. 

For PEX only cold expansion, insert and compression fittings are allowed. 

Trenches that are deeper than the footing of the structure need to follow a special rule. 

Water from a faucet on a sink should have a flow rate between 20 and 60 psi.

Shower heads have to be approved and follow the local regulations.

The drain of the shower should be wider than 2 inches. 

The shower surround should be waterproof.

The showerhead shouldn’t be installed at the entrance of the shower. This allows the user to adjust the temperature without having to stand under the showerhead. 

Dishwashers need an air gap fitting.

Commercial and public buildings have special requirements that are described in more detail in the plumbing code. 

Water heaters

There are requirements for the inlet of fresh air and how the dirty air is pushed outside (such as the chimney).

There are requirements when it comes to the electricity that is provided to these systems (if applicable).  

Water supply and distribution

Faucets with water that is not drinkable should be marked. 

PVC and PP can’t be used to distribute water.

A lot of this comes down to buying the right materials in a hardware shop in California.

Water supply lines can’t be in the same drench as waste drains.

Water hammer arrestors are required in some cases.

Each type of fixture has its own requirements when it comes to the size of the water supply pipe.

Sanitary drainage

There are limitations as to where you can use PVC, PE, galvanized steel, and stainless steel. 

The size of the drain depends on the type of fixture and the number of fixtures that are connected.

Indirect waste

Approval is needed before you can install these.

Pipes transporting water from pools should be installed as indirect waste. 


The size, location, and materials of the vents are regulated.

Buy these materials in a store in California and you should be generally good to go. Just install them in the right place and seal them properly. 

Traps and interceptors

Traps should be generally self-cleaning.

Industrial sites have special requirements when it comes to installing and using traps. The goal is to keep oils and fats out of the wastewater system.

Storm drainage

These are required in a lot of areas. For most houses, this means that gutters need to be installed. Subsystems such as cleanouts can also be needed.

If there have been alterations to the system, it has to be tested again to make sure that it works properly.

Firestop protection

Pipes that go through walls might have to be protected by additional fireproof materials. This will be inspected so it is essential to get this right. There are special materials on the market that make this quite easy to do.

Alternate water sources for nonpotable applications

Drawings have to be created for these systems.
The soil composition might have to be checked to make sure that it is suitable for a greywater system or septic drain fields.

There are quality requirements for recycled water. 

Nonpotable rainwater catchment systems

A permit is needed for this type of system. The system will be tested and inspected before you can use it.

There are requirements when it comes to water quality. 

To conclude, we have outlined some of the code requirements for plumbing systems in California. We have just scratched the surface as there are a lot of things that you have to take into account. A lot of it comes down to buying materials that have been approved for usage in California. 

If you are unsure how to install something, it is possible to reach out to the local regulator or your inspector. Some situations can be unclear. If your inspector signed off before you installed it, you are sure that you are doing the right thing. This will avoid costly repairs or rework. 

While it might take some time to learn about the plumbing code, this system makes sure that there are no problems with your plumbing installation. This avoids a lot of issues and damage later on. 

The full guide can be found here:

California: rules about installing a toilet

Toilets have to comply with the WaterSense standard that is set forward by the EPA. The baseline is 1.6 gallons per flush.

The clear space in front of the toilet has to be at least 24 inches, on the side, it has to be at least 15 inches. Urinals have other requirements.

Copper alloy, hard lead, ABS, PVC or iron flanges have to be used to connect the toilet to the drains. You also have to use approved rubber gaskets and other components. 

Wall-mounted toilets have to be hung with an approved system.

Floor-mounted toilets have to be installed level with the floor. 

Some systems can’t be installed. Toilets have to follow the local rules. The best way to do this is to buy the toilet and parts in a local hardware store.

Toilets are sometimes flushed with rainwater. There are special rules for this. These include water quality requirements.

There are also rules for macerating toilets. These toilets are generally installed in a basement. The goal is to pump the sewage away as the toilet can be below the main drain line. These systems have to comply with certain standards.

There are rules for common toilets as well (for example, fountains can’t be installed in toilet rooms). We won’t discuss these in detail as these are not present in residential buildings.

Greywater can’t come in contact with the toilet sewage water.

 A backflow valve is required.

Sewage discharge systems need a discharge capacity of at least 20 gpm.

Proper venting systems and traps are needed.

Dry or chemical toilets need approval before they can be installed in a building where humans live.

CA: rules related to installing a shower

Residential showerheads should limit the usage of water to 1.8 gallons with a psi (or water pressure) of 80. Showerheads have to follow the local rules and be approved.

120 degrees Fahrenheit is the maximum temperature of individual shower heads. 

The drains should be at least 2 inches wide. Only approved materials can be used for this.

There are requirements for the shower curb and shower receptor. Only purchase materials that are approved by the state to make sure that you comply with these. If you don’t use a shower receptor or use a small one, you might have to use additional materials to install the shower enclosure.

Shower seats also have specific requirements. 

Shower doors should create an opening of at least 22 inches. There are other size requirements for the shower itself.

Shower linings should be waterproof and made out of approved materials. 

California: septic system requirements and rules

These systems have to be approved before they can be installed. Inspection will be done before they can be used. The soil affects how the system has to be installed and what is possible.

The system has to be watertight. It will be filled with water to test this.

Commercial buildings might need a special disposal system for fats and other liquids that could affect the soil.

There are a lot of local septic system rules so check with your local administration to see what is feasible in your area. 

CA kitchen and bathroom sink and faucet

Sinks need a p-trap. Only approved materials can be used for the drain. Gray water has to be separated from toilet waste water. 

For kitchen faucets, the maximum flow rate is 1.8 gallons per minute at a psi of 60. This can be increased slightly for limited periods of time. 

Once again, the easiest way to be sure that everything is compliant is by buying the faucets in a local hardware store that stocks approved materials. 

The previous list is not exhaustive and you should check the local plumbing code in more detail before you install a new system or work on an existing one. It is possible that the code has been updated or that there are typos or mistakes in the previous text. Check the code book to verify. 

Check for more info.