GPM table

Does anyone have a table that lists the gallons per minute (assumed) of the plumbing fixtures of a home? I’m starting to do septic load inspections, and need to be able to calculate the amount of water I’m introducing into the system.

Thanks in advance.

bump. Anyone?

I realize this isn’t exactly what you’re looking for, but maybe it will offer some info you can use…


for proper accuracy you will have to measure each fixture’s actual flow which depends on pipe sizes, water pressure…
The water audit spreadsheet is a useful tool to evaluate water use in the home.

I don’t what your asking for is practical Mark.

There are so many different faucet types.

Example: A typical brass laundry sink faucet is wide open but a lav or kitchen sink haves a aerators and are much lower flow rate fixtures.

Basically, I need a way to figure out “about” how much water I’m introducing into the septic system. For example, if a bath tub (in general) will produce about 2.5 gpm, and I run two tubs at the same time, I know I need to run the water for 10 minutes to introduce 50 gallons to the septic tank.

It’s understood that individual fixtures will vary, but it’s accepted that this type of math is acceptable for doing the calculations that are required.

How about a stop watch and a gallon jug Mark. :wink:

I have to ask this one , Why would you need to know this?Is it going to be a design type thing? or a existing tank and field?
You could alawys turn everything on check the gallons used at the meter if it is on a well installed a flow meter

That would work, but take too much time in an already very time consuming inspection.

I was told by the instructor (who wrote many of the state policies and procedures) that there was a table that listed this information that we could use.

I need to know it, because it is a state law that a stress test of a certain number of gallons needs to be put through the system. It’s for existing systems. The meter would work assuming it is there and assuming it is functioning properly. Two assumptions that will only hold for a certain number of inspections.

Mark; hope something in one these links help

Septic Systems
Understanding Your Septic System…umbingcode.pdf…er/septic.html…additives.html
Septic Load and Dye Test Poll…ter_Volume.htm


I am not a engineer but there is no way of being exact , It depends on pressure which would be up and down. So average would come in to play. My thought would be size of line, amount of fixtures . Then there is a problem if the septic system has been maintained . What if the septic lines are partiality plugged? I have a flow meter i use to test for wells and yes it is only approximate . i would think if you sized the main water line 3/4 or 1/2 inch for flow
I know you probably have this but just in case

Not necessarally true, you may have 2.5 GPM on a faucet, but it may be reduced somewhat when you use other fixtures. The only accurate way to determine this, would be to use a meter like the one Nick is selling, and measure the GPM while another is in use. Even still, you will never be able to get it exact due to so many variables.JMO

You can have perfect pressure and still have a low flow rate. Volume and pressure are two different things.

All of that is understood. The numbers needed are generic averages, not engineering specific.

Anyway, after about 2 hours of turning pages in my State Basic installers course book, and then again in my State inspectors book, I found the reference page. I’ve attached a PDF of the relevant info for anyone else who is interested.

Thank you all for the very informative links. Wish we still had the greenie system so I could give a tangible thanks as well.

10-4 thanks for the info.