1/2" service line too small?

Hi -

I'm in Seattle and in the process of adding a second bathroom to a 1920 house. I've got a 1/2" galvanized line running from the meter into the house, from that entrance it opens out to 3/4" copper for distribution thru the house. The meter (at the sidewalk) is marked 3/4"-5/8", the 3/4" marked on the house side outlet -- but I am absolutely sure the line to the house is 1/2".

I'm feeling like I need at least a 3/4" service line to the meter to maintain adequate volume. Would you experts agree? It seems the shower is sensitive enough to other minor water use; it would be cool to run 2 showers satisfactorily. What seems limiting is the 5/8" inlet marked on the city meter. Has anyone worked with these and do I have much to gain by dropping in a bigger line on my side of the meter?

Thanks!
Kurt

Seattle uses the UPC plumbing code.
With a 5/8" water meter and two bathrooms, you should have at least a 1" water service.

https://terrylove.com/watersize.htm

Thanks Terry... working late I guess?

So run a 1" line from a 5/8" - 3/4"meter? Would that be a special adapter or can it be done with off-the-shelf pieces?

The City of Seattle website say their new meters allow 50-100% more flow for the same size meter as older models. Is this believable in your opinion? Should I try to get a meter upgrade from the city?

Thanks again

It is easy to change sizes. Not only is the 1/2" pipe too small, galvanized pipe as old as yours is probably almost corroded shut! 3/4" would probably be enough, but for the slight difference in cost, I'd go with 1" pipe.

A 3/4 pipe is not enough with the 5/8" meter.
Code calls for 1" pipe in Seattle.
Seattle is very picky about water service sizing.
Most new three bath homes are now being plumbed with 1-1/4" lines.
Make sure you have the right pipe size or the plumbing inspector is going to turn the job down.

The cost difference between doing it right and not doing it right is about $10
The 5/8" meter should be fine. It will have 3/4" threads at the sidewalk, and you can increase from there.

pipe

Here the decision to use 3/4", 1", or larger is determined by the length of the line and the load on it.

OK, I'll go with 1" from meter to house.

Do I need the city to get me a meter larger than 5/8" bore, like 3/4"?

Thanks

Terry said:

3/4 pipe is not enough.

Code calls for 1" pipe in Seattle.
Don't tell someone that 3/4 will work when the plumbing inspector is going to turn the job down.

The cost difference between doing it right and not doing it right is about $10

Click to expand...

A 5/8 meter and a 1" main are suffice given the limited info you supplied.