RV Water Pressure Regulators & Related Matters

As promised, here is some information on RV water pressure, water flow, and water pressure regulators.

I'll start with this easy to understand narrative from Rick & Lynn Dahl's RV Water Filter Store's "Water Flow & Pressure Page".  Rick's words are italicized and then I've added a few editorial comments here and there.

Low Pressure will Drive you Crazy - High Pressure will Burst your Pipes - What's a Person to Do?

One of the biggest complaints we hear from customers is that they don't have the right water pressure supplied to their RV. It's usually too low, and they can't get enough water to take a decent shower. Sometimes, it's too high, and they are afraid of bursting their plumbing. From our experience on the road, we know that you will encounter both types of problems, but there are very reliable ways of overcoming them. First, let's explore the problems in more detail.

Pressure or Flow - What's the Problem?
Many people don't understand the difference between pressure and flow, but you need to in order to solve your problem. "Flow" is a measure of volume of water delivered in a period of time. The poor shower is caused by low flow, as are most other RV water supply problems. "Pressure" is a measure of the force of the water, and it is measured when no water is flowing ("static" pressure). It is true that for a given plumbing system, the higher the pressure, the better the flow. However, there is a practical limit to increasing pressure to improve flow.

Flow is measured in gallons per minute (gpm).  Pressure is measured in pounds per square inch (psi).

By the phrase "when no water is flowing", Rick means when the water is turned on at the campground spigot, but no water is turned on inside the RV.  In other words, "static pressure" is the pressure being put on the RV plumbing system when there is no release of the pressure inside the rig.

Don't Let Your Pressure Get Too High
RV plumbing systems are usually tested to a pressure of about 100 to125 pounds per square inch (psi), but to prevent warranty problems, RV manufacturers may recommend only 40-50 psi. Unfortunately, this may not provide the shower you're looking for. Most house plumbing operates at about 60psi, and this can be adequate for RVs, too. If your water supply pressure is approaching 100 psi, you are risking an expensive failure of your plumbing system. You should limit your pressure to 60-65 psi to be safe, and to do that, you can install a pressure regulator.

In addition to manufacturers recommending 40 - 50 psi, many owner's manuals say "Always use a pressure regulator".  And, if your RV is older, that 60-65 psi range Rick gave may be too high.
 
Causes of Low Flow in RVs
Size matters, particularly in regard to water flow through pipes and orifices, and the bigger the better. Anything that reduces size in a plumbing system creates a restriction to flow. Restrictions can occur at any point in your RV from the park's valve to your kitchen sink or shower, and they are cumulative. Several modest restrictions in your plumbing system can drastically reduce the flow at the shower head. So, let's start at the beginning of your water supply line and look at causes of restriction and fixes available.

It Starts With The Hose
The hose you use to connect your RV to the water supply may be the first cause of flow restriction. Many RV water hoses are pretty cheap, and they are prone to kinking or collapsing. If your hose does that, you are suffering from a flow restriction. The solution here is to use a better hose that resists deformation.

Most of the white RV/marine hoses you see at RV dealers, Walmart, or Camping World will be fine.  However, they come in various diameters, lengths, and psi ratings.  Definitely check the psi rating.  Also, the larger the diameter, the better the flow.  Most are 1/2-inch and 5/8-inch.

Rick recommends against the thin, coil-type hoses.  While they may restrict flow, the bigger issue is that they are often clear which can lead to the production of algae when they sit in the sun.  Algae can plug up filters and other components fast. 

Rick sells only 1/2-inch industrial strength hoses rated to 200 psi.  And that leads to another question.  "Do you install the regulator at the spigot or at the RV water inlet?"

Well, opinions vary, but if your hose is rated for 100 psi or less, I'd recommend putting the regulator at the spigot to protect your hose.  I've heard far more stories of hoses exploding than RV plumbing giving out.

A personal story.  In the very first campground we ever went to as full-timers, I didn't have enough white potable water hose to reach the spigot.  Being a complete novice, I thought "It won't hurt to hook up the garden hose we brought to make it reach - just this one time."  I don't recall now if I had a pressure regulator on or not - if I did, it was one of those cheapies, the kind they sell you when you buy a new rig.  But, on our third day .... Ka-blewy!  The garden hose exploded.  Water came in our windows, and there was a geyser in our yard.  Yep, it took all of three days to convince me about the need for quality hoses and pressure regulators.  :)

Pressure Regulators Also Cut Flow
We talked about pressure regulators earlier and think they are a wise investment. However, while protecting you from excess pressure, they may be seriously reducing your flow. Like many plumbing fittings, regulators inherently restrict flow, but some are worse than others. Generally speaking, the more expensive regulators can accommodate a much greater flow of water than the cheap ones. We sell a complete line of pressure regulators, including industrial-strength, high-flow, adjustable units.

This is the regulator we started out with.

It's the basic, cheap one most people get when they first start this RVing thing.  It says right on it that it is "Preset at 45 psi".  Well, we learned later that 1) the plumbing in newer RVs can handle more than that, and 2) this regulator severly restricts "flow".

We learned that second piece in quite the unscientific manner.  Water would gush from the spigot, but after installing the regulator, the flow inside our rig would be very low.  Still, we always put it on.

Eventually, we bought a larger regulator with a higher gpm rating and with a gauge - the Watts IR56 with a gpm of 3 - 3.5 gpm (that regulator has since been discontinued).  And recently, we bought an even larger regulator with a gauge that has an even higher gpm rating - the Watts 263A with a gpm rating of 4 - 4.5 gpm AND it is adjustable up to 160 psi.

Pressure regulators need to be either replaced or taken apart and cleaned every couple of years.  The higher quality Watts regulators can be disassembled and cleaned and there are re-build kits for them to make them last even longer without having to re-purchase new ones.

Filters Can Reduce Flow Significantly
Filters work by forcing water through very small orifices to strain out the contaminants. Fortunately, there are a huge number of "holes" in a filter, and the bigger the filter unit, the more "holes" it has, and the better the flow. So, to achieve better flow through a filter, use a bigger filter that has more filtration area. A small, in-line filter restricts flow more than a 10-inch standard canister, and the standard canister is more restrictive than a jumbo canister. So, if you are using filtration on all of the water used in your RV, you will want to go with the largest filtration system that will fit your needs to avoid flow restrictions. Another factor to consider with filters is that as they get plugged with contaminants, their flow rate decreases. If you find your flow rate dropping when you are using filters, it may be time to clean or replace them.

Most of us RVers filter the water coming into our rig.  Some of us filter it two or three times.

Even though we have a "whole-house" filter inside our rig, a certified RV tech, that taught courses with us at Life On Wheels, told us to always have a sediment filter between the water spigot and our fresh water inlet.  He said to never let any more sediment into the plumbing system than absolutely necessary.

So, we use a cheap in-line filter at the spigot, and then we have a canister-type filter in the rig.  Then, for drinking water, we use a Brita pitcher to filter it a third time.

Many people double or triple-filter their water with canisters outside the rig or a combination of canisters inside and/or outside.  Filters are a whole different discussion, so I won't go into any more detail.  Peruse the RV Water Filter Store site for more information about filtration.

The bottom line, for the purpose of this discussion, is that filters restrict flow.  And filters eventually get clogged.

This was another lesson we learned early on.  When we noticed a decrease in flow, I did some research and found information on the filter topic.  I replaced the filter cartridge in our canister filter and we were back to normal.

Internal Plumbing Systems may Be Inadequate
Manufacturers will scrimp on anything and everything to cut costs, and this includes the plumbing system. Undersize pipe and restrictive fittings can contribute to the low-flow problems you experience. If you check the flow in a brand new RV that is hooked up to a municipal water system, everything may look good. But, if you take this same rig out to an RV park and hook up a pressure regulator and a filter, it may suffer. Unfortunately, there is not much you can reasonably do to improve an RV's plumbing.

Fixtures Can Also Seriously Reduce Flow
Your plumbing fixtures are the final place that flow restrictions can occur. Sink faucets and shower valves often have very small orifices that seriously limit the amount of water that can pass through them. Sometimes, these restrictions are removable, and are included to meet Federal water consumption standards. In any case, you can find better-flowing fixtures by carefully shopping around.

We have also experienced low flow at our fixtures.  We replaced the factory shower fixture with one allowing better flow.  It was so easy, even I could do it.  :)

Our kitchen faucet also has low flow, but it matches all our other hardware in the kitchen, and we can't find anything else quite like it.  So Linda suffers with that one.  We've had it apart and it's not quite as easy to deal with as the shower.  :)

So, if your water "pressure" is not what you think it should be, it could be the result of

• Low pressure from the campground
• Low flow rate from your hose
• Low flow due to your water pressure regulator
• Low flow due to low capacity water filters or clogged water filters
• Low flow due to internal RV plumbing
• Low flow due to restrictors or small orifices in individual fixtures
• A combination of any or all of the above - Remember the flow problems are "cumulative" as the water flows through each component

Okay, so if we go back to the discussion of water pressure regulators, one question is "Do you really need one at all?"

Most full-timers will give you an unequivocal "Yes!".  Though there are many people on the road that say they've never used a water pressure regulator in their 10, 20, or 30 years of RVing and never had a problem, it just takes one busted pipe or fitting in your RV while you are gone to re-think that position.

It's another of those really cheap insurance things, and though they aren't what I could call common, there are enough RV parks and campgrounds out there with water pressures in the 100 psi and above range to make it really, really risky without a regulator.

Now, some people use a pressure gauge when they arrive at a campground.  They'll hook up the gauge to the spigot with a cap on the other side to gauge the water pressure before hooking up their hose.  If the pressure is, for example, 40 psi or below, they may remove the pressure regulator so as not to restrict flow any more than necessary, and if it is higher than that, they will usually leave it on.

Of course, if the campground is full and there is a big percentage of sites using water at the time you arrive, the pressure you see may be much lower than the overnight pressure when no one is using water.  Just something to consider.

Also, when water is heated it expands.  Although I can't find definitive guidelines on this, I've read a couple of different places where in-house water pressure gauges have shown a significant increase in psi in the RV when the RV water heater is on.  Reports on how much the pressure increases varies.

When heating water, the water in the water heater expands.  There is a naturally occuring air bubble in the top of the water heater to allow for this expansion.  If the bubble gets filled with expanding water, the built-in pressure relief valve in the water heater is designed to relieve the pressure and water will drip or weep from the valve.  That dripping/weeping is normal.

Here is a FAQ from the Suburban RV Water Heater website.

Why does water drip from my water heater's pressure and temperature (P&T) relief valve?

You may experience water weeping or dripping from your water heater's pressure and temperature (P&T) relief valve when your water heater is operating. Water weeping or dripping does not mean that the P&T valve is defective. As water is heated, it expands. The water system in a recreational vehicle is a closed system and does not allow for the expansion of heated water. When the pressure of the water system exceeds the relieving point of the P&T valve, the valve will relieve the excess pressure.

One way to reduce the frequency of this occurrence is to maintain an air pocket at the top of the water heater tank. This air pocket will form in the tank by design - however, it will be reduced over time by the everyday use of your water heater. To replenish this air pocket:

1. Turn off the water heater.
2. Turn off the cold water supply line.
3. Open a faucet in the RV.
4. Pull out the handle of the pressure relief (P&T) valve and allow water to flow from the valve until it stops.
5. Release the handle on the P&T valve - it should snap closed.
6. Close the faucet and turn on the cold water supply. As the tank fills, the air pocket will develop. Repeat this procedure as often as needed to reduce the frequency of the weeping P&T valve. If the weeping persists after following this procedure, you may elect to have your dealer install an expansion or accumulator tank in the cold water line between the tank and check valve to relieve the pressure caused by thermal expansion.

An accumulator tank can serve the dual purpose of 1) providing additional space for expanding water in the system and 2) providing smoother, quieter, more energy efficient operation of your water pump when not on water hook-ups. 

So, when the water is expanding, if there is no accumulator tank and the bubble in the water heater is gone, there has to be additional pressure building up in the system.  Does the pressure relief valve fix that problem?  Or does it just relieve the necessary pressure from the water heater alone?  I'm not sure about that, but pressure relief valve failure seems like a really big problem for the water heater and the plumbing system.

Now, continuing the water heater discussion, there are two schools of thought on whether to leave the water heater on all the time or to just turn it on and heat water for showers/dishes when needed.  Both camps have valid reasoning.

We fall into the "heat when necessary" camp, mostly because Linda simply doesn't like to leave anything with a heating element on for long periords, especially when we're not home.  Now that we have an adjustable water pressure regulator that we set at about 60 psi, we will certainly be more conscious about leaving the water heater on as it may cause our plumbing system to push its psi limits with the expanded heated water.  When we leave the rig, we always turn off the water heater, but we'll be more diligent about double-checking it now that I've learned about the potential increases in pressure.

Some RVers completely shut off the water at the spigot whenever they leave their RV.  That way there are no pipe or connection or fixture failure issues that could cause flooding while gone.  We only do that if we're going to be gone overnight or for a few days.  Shutting down the water supply completely every time you leave seems like a hassle, but it certainly eliminates a lot of worries while you are gone.  :)

Is a water pressure regulator a good idea?  Yes.  Does it restrict flow?  Yes.  But there are ways to regulate the pressure and still get good flow.

Of course, the biggest problem is the one you can't control at all - the flow and pressure from the campground spigot.  But, in low pressure situations, at least you can make sure you can get the best possible results you can get.  :)

However, sometimes that's not good enough.  So many of us fill our fresh water tank and use our water pump.  Often that pressure and flow is better, especially if you have an accumulator tank (which we don't have).  But, keep in mind that water pumps also are rated by flow or gallons per minute.

If you want to have good flow from your water pump, the higher the gpm, the better.  But, if you like to boondock and you want to conserve water, perhaps the higher gpm pumps aren't the best for you.

And people think this RVing thing is easy.  :)

Lots of variables, lots of decisions, lots of differing lifestyle choices.  Our only hope is that we help you think through a few of them.  :)

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Comments

[Cindy T]

Howard,
Thanks so much for sharing this info! It is really helpful!

[Sherry Boyd]

WOW Howard this is FANTASTIC! Thank you so much for all this information in one place. SO helpful to those of us who are just beginning to get a clue.

LOVE this journal and the entire web site.

Sherry

[Robbie & Alice Simons]

Howard, we use the same regulator but in the stainless steel model; it supposedly cuts down on a possible rust problem.

Also, if you are in a park with low flow/pressure, we have found that the combination of using the park water and the onboard pump makes for a nice shower.

[Rod Ivers]

Nice review of water pressure and regulators. We just had the tail lines of our kitchen faucet burst, this weekend. It filled our drawers full of water for about an hour before we got back home. We were using the little 45 pound pressure regulator, and the CG owner said he had trouble getting 60 lbs from the rural water system that they were hooked up to. We may never know the why, but I know a regulator is a must. See RetiredRod.blogspot.com for the blow by blow.

Thanks again for the good review.

[Craig]

Great info Howard, as always. As far as flow goes, have you ever looked at how small the hole is INSIDE a hose bib that the water must flow thru before it exits. I always wondered why big supply lines mattered in this scenario. Must be a engineering thing... :) Thanks again.

[john]

indeed great info for those of us that are novices to the world of RV'ing...

[Jerry & Carol]

Great information. What about using on demand water heaters instead of tank type heaters? Would that serve the purpose of getting hot water when needed without the need for keeping a tank of hot water? Just curious about that.

[emery Nash]

Good info, Howard.

One other often overlooked source of flow restriction is the check valve that is usually behind or a part of the shore water inlet connection. These often have surprisingly low flow ratings given the RV they are installed in and can be the single most restrictive element in the whole freshwater chain.

They do go bad, too, and can become even more restrictive as they begin to fail.

[emery Nash]

Trying to determine if a check valve is causing a low flow condition can be difficult but often an easy way to bypass it is to attach a brass garden hose adapter to the freshwater system drain (presuming it has a threaded vent end on it)and open the drain. This will let the water come directly into the fresh water system and bypass the check valve. If you have considerably more flow from this supply, the check valve may the be restricting element in the system.

[hose adapters]

Great post. I feel exhausted but I enjoyed reading it because I learned so much from it.

Angelo H

[Marty Flatau]

Does an RV water pressure regulator protect against air pressure also?

For example, if I have a brass Camco 50-psi water pressure regulator installed on my camper, will that regulator provide any degree of protection against air pressure when I winterize my camper by blowing air into the water lines to clear them?

[Howard]

Marty,
I have no idea if a water pressure regulator will protect against air pressure as well. I know there are regulators designed to do both, but I'm not sure if one specifically designed for water will. It would seem to me that perhaps the application of water through the regulator might be necessary for it to work as designed, but I could be completely wrong. :)

[meaganadams0402@yahoo.com]

I am writing because we went on vacation a week ago in our fifth wheel, our water pressure was same as always then, the rv sat in storage for a week, and today we got to a new destination hooked up to the park water and our water pressure in the bathroom is normal, but the kitchen sink has none, it just dribbles out, we can not find the cause and are in desperate need of advice

[Selene McGraw]

It's amazing how these regulators can be replaced or taken apart and cleaned occasionally. This can definitely help reduce my water consumption at home.

[BUJoeCool]

As an engineer I agree that a water pressure regulator is a great idea for your RV (and home for that matter). As a father, I am disappointed that there has been no discussion about the fact that most of the pressure regulators sold for RV's are NOT LEAD FREE. I actually find it very ironic that a company that specializes in RV water filtration is selling regulators that contain lead. Watts does have some Lead Free regulators, but none of them are sold at the site mentioned at the beginning of this article. Do yourself and your family a favor, make sure that you are using Lead Free components for your drinking water supply.

[Dee Gaida]

The water line broke explosively just like that. Husband had to go outside to shut off the water as apparently the shutoff behind the toilet blew right off! He is hone to gt a new shutoff but I am questioning hy that much pressure is on those fixtures? We re in a prk model trailer in a big park, trailer is 2 years old, never had this problem before. Water pressure in sinks and showe is fine. Any suggestion s?