Plumbing Order of devices in the main water line?

[Stephen Tashi]

TL;DR Summary

What devices are useful on the "city's side" of a main water line? In what order should they be installed?

I have a house where water enters from the street in a 1" PEX line, which comes up from the slab inside a closet. No other permanent plumbing is yet installed. I want to install a shut-off valve, a pressure regulator, pressure valve, and a sediment filter. I'm also considering installing a water hammer arrestor if that is useful combating water hammer coming from the city's plumbing operations.

Is the best order for these devices (starting at the city's end of the line): shut-off valve, pressure regulator, pressure valve, sediment filter? Does the pressure regulator combat water hammer coming from the city's end? If not, should the water hammer arrestor be installed just after the shut-off valve?

 

[BillTre]

I would put the shutoff valve first and the sediment filter next to keep debris out of the pressure valve and regulator (which might be mess-ap-able by sediment getting into them).

But realistically, I would look for a professionally informed person than me for something like this.

What's the difference between the pressure regulator and the pressure valve?

 

[Stephen Tashi]

What's the difference between the pressure regulator and the pressure valve?

I meant to say a "pressure gauge" instead of a "pressure valve".

 

[BillTre]

Gauge after regulator then.

 

[ChemAir]

You may have some local requirements for a check valve or backflow preventer. It may be best to call the municipality to be sure local requirements are met. They may require some specific order for installation.

 

[AK_NC]

As a plumber in NC this is what we do. Whole house shut off ball valve, PRV, expansion tank rather than an expansion valve. Typically there is no need for a sediment filter on city water, your local water quality may be different though. Y stariner may be all you need to protect your house from city water debris. 2 stage carbon filter under the sink will take away any chlorine taste from city water. Any residential filter is designed to work on house pressure, max 80psi, not on city pressure. Water hammer arrestors aren't typically necessary with a new PRV, especially with pex, but can be easily added at your washing machine box if needed. Your new PRV is adjustable when you install it, but not years later, set it at the beginning and leave it. Match your expansion tank pressure to house pressure. Typically I inflate them to 60 psi, then adjust the PRV to match. Both wear out with time. Check air pressure in tank and house pressure at a hose bibb every year, replace components when they fail. Definately consult with your local plumbers or even the building department, local standards may be different.

 

[Asymptotic]

Depending on budget and city water supply quality you might consider installing an adequately pressure rated Y-strainer after the mains shutoff. A #40 to #60 screen will block bigger stuff from getting into the regulator, and reduce dirt load on the finer filter element.

If you opt to use a filter it's a good idea to install a shutoff valve on the downstream, "clean" side so (in conjunction with shutting off the mains valve) it can be isolated from the system for element replacement without the need to drain the system. Most filter housings come equipped with a pushbutton relief valve and/or a drain cock at the low point so interior pressure can be equalized with atmosphere. If the housing doesn't, then add a valve on the dirty side open to atmosphere. Even a tiny amount of residual pressure in the housing makes unscrewing the clamp ring difficult.

This comes from an industrial perspective, but when space allowed I'd gotten into the practice of installing tees on the source and usage side, and installing shutoff valves (usually plugged too, in case the valves were opened accidentally) so adding unanticipated gear, or performing infrequently required tests (for instance, checking city water pressure) was readily possible and practical.