How To Look At A House

McGarry and Madsen's home inspection blog for buyers of  

site-built, mobile/manufactured and modular homes

What are the building code requirements for gray water reuse in Florida?

Tuesday, June 19, 2018

Gray water systems are allowed only for flushing toilets and urinals, and setting up one is not a simple project. To start with, the Residential Edition of the Florida Building Code (FBC) has specific  limitations on what water can be reused:

    Kitchen sink waste water is not on the list because of the high organic content from bits of food waste, which would increase bacterial activity in the water. Florida does allow clothes washer water to be recycled, although some other states do not. The likelihood of small amounts of fecal matter in underwear, and significantly more fecal residue in diapers, getting into the gray water is the problem that concerns the states that prohibit it.

    Additional requirements of the code include:

  •  Gray water must be collected in an approved reservoir constructed of durable, non-absorbent, and corrosion-resistant material. The reservoir should be closed, with access openings for inspecting and cleaning the interior.
  • The reservoir should be vented.
  • Gray water has to first pass through an approved filter before entering the reservoir.
  • A full-open valve needs to be installed downstream of the last plumbing fixture before the water enters the reservoir. A “full-open” valve is one that does not restrict the flow of water when open all the way.
  • The reservoir must have an overflow pipe of the same diameter as the inflow pipe. The overflow must be trapped and indirectly connected to the home’s drainage system.
  • A drain should be installed at the lowest point of the reservoir, of the same diameter as the outflow pipe, and indirectly connected to the home’s drainage system. 
  • The collection reservoir is required to have a capacity of at least twice the daily volume of water needed for flushing the fixtures, but a minimum of 50 gallons. 
  • The reservoir must be of a small enough size to limit the retention time of the gray water to 72 hours.
  • The gray water needs to be disinfected by an approved method, such as chlorine bleach, and tinted blue or green with vegetable dye.
  • Potable water must be supplied for makeup water as necessary, and the potable water connection will have a backflow prevention device.
  • Both the reservoir and pipes shall be clearly marked as containing non-potable water. 

• • • • • • • • • • • • • • • • • • • • • • • • • • • •

Here’s links to a collection of our other blog posts about PLUMBING:

How can I protect my pipes to keep them from bursting during a hard winter freeze in North Florida?

Why is there sand in the bottom of my toilet tank?  

What causes a gurgling sound when a bathtub or sink drains? 

Are drop-in toilet bowl cleaner tablets safe? 

What can I add to my septic tank to help it work better?

What are the code requirements for layout of drain piping under sinks? 

Are plastic pipes (PVC, CPVC, and PEX) safe for drinking water? 

Why is a backflow preventer required on lawn sprinkler systems? 

How can I locate my septic tank? 

Is a hot water faucet handle required to be on the left? 

Can you live in a house while the plumbing is being replaced? 

Why is the European-style bottle trap not approved by the plumbing codes in the U.S.? 

Why can't PVC be used for water pipe inside a house? 

What are the common problems to look for when the plumbing has been replaced in a house? 

What's that powdery crust on the pipe connections at the water heater? 

How can I tell what type of plumbing pipe I have? 

What causes low water pressure in a house?

Should I call a plumber or septic tank contractor when my septic tank backs up into the house? 

How do I get rid of the sewer gas smell in my house?  

What are the pipes on my roof? 

Should I wrap the water heater with an insulation blanket? 

My water bill went way up last month. How do I look for a leak?

Why does the water have a rotten-egg smell in some empty houses? 

What is an "S-Trap" under my sink? Why is it a problem? 

Where is the septic tank? Are you going to inspect it? 

What does polybutylene pipe look like? Why is it a problem?

Which water pipes are an insurance problem and possibly uninsurable? 

• Does a home inspector check the plumbing under the floor slab?

• Is it alright to disconnect the washing machine drain from the septic tank and divert it to the ground in the yard?

      Visit our PLUMBING page for other related blog posts on this subject, or go to the INDEX for a complete listing of all our articles.  

Water Heaters

Water Heater Age

"What Are The

Signs Of..."

Septic Tank Systems

Structure and Rooms

Plumbing Pipes

Termites, Wood Rot

& Pests



When It First

Became Code

"Should I Buy A..."

Park Model Homes


Shingle Roofs




Wind Mitigation

Roof and Attic

"Does A Home


Pool and Spa

"What Is The Difference Between..."




Concrete and

Concrete Block

Metal Roofs


Modular Homes

Rain Gutters

Mold, Lead & Other Contaminants


Older and

Historic Houses

Crawl Spaces

Mobile-Manufactured Homes

Building Permits

Life Expectancy

Clay Soil





Exterior Walls

& Structures


Common Problems

HUD-Code for

Mobile Homes

Garages and Carports

Flat (Low Slope) Roofs

Electrical Panels

Sprinkler Systems

Electrical Receptacle Outlets

4-Point Inspections

Hurricane Resistance

Frequently Asked Questions (FAQ)

Home Inspection

Heating and Air Conditioning

Building Codes

Fireplaces and Chimneys

Inspector Licensing

& Standards

Energy Efficiency

Washers and Dryers



Doors and Windows



Electrical Wiring

Click Below  

for Links

to Collections

of Blog Posts

by Subject

Plumbing Drains

and Traps


Smoke & CO Alarms

Aging in Place

Top 5 results given instantly.

Click on magnifying glass

for all search results.






Air Conditioner & Furnace Age/Size


Electrical Switches





Water Intrusion

Electrical - Old

and Obsolete


Foundation Certifications

Tiny Houses

About McGarry and Madsen



Buying a home in North/Central Florida? Check our price for a  team inspection by two FL-licensed contractors and inspectors. Over 8,500 inspections completed in 20+ years. In a hurry? We will get it done for you.

Moisture Problems

Crawl Spaces