Water Line Replacement

[bubblegummom]

We may have to have our water line replaced from the meter to the house. What kind of pipe should it be replaced with?

Loretta

[LazyPup]

For direct burial water supply lines both the IRC(International Residential Code) & UPC(Uniform Plumbing Code) will allow;

Brass Pipe,
Copper Pipe-(types K,L&M in both hard drawn rigid lengths & annealled roll pipe )
CPVC
Ductile Iron Pipe
Galvanized Steel Pipe
PE (Polyethelene) Plastic Pipe
PE (Polyethelene) Plastic Tubing
PEX Plastic Tubing
PVC Plastic Pipe

The IRC will also allow ABS Plastic pipe, PB(polybutelene) plastic pipe, & PEX-AL-PEX pipe.

We can quickly rule out Brass pipe because it is very difficult to locate, extremely expensive and very labor intensive to install.

Generally we can then rule out Ductile Iron Pipe & Galvanized Steel Pipe because they are both expensive, very labor intensive to install and due to internal fouling from rust & mineral scaling they have a relatively short expected life of about 30 to 40yrs.

This then leaves us Copper & Plastic pipes.

Hard Drawn Copper PIpe, PVC pipe & Cpvc pipe are made in rigid 10' or 20' lengths, which means you will need a joint every 10" or 20' and at each change in direction. Considering that most failures occur at joints it is then fairly easy to rule these out, not to mention that currently copper is extremely expensive. It should also be noted that because these pipe are rigid they require very careful attention to properly bedding them in the trench so they are not subject to stresses from an uneven trench.

PB Pipe-When PB pipe first hit the market in the early 80's it took off like a wildfire and was touted to be the material of choice for high end construction, but due to a very high instance of failure in PB pipe fittings there were hundreds of class action suites filed against the material and the codes were quickly ammended to prohibit using PB pipe inside a structure. As a result, even though it is code approved for supply pipe, I personally don't know any suppliers who carry it, and very few are even willing to get it on special order.

We are now left with a choice between PE & PEX.

Both PE & PEX are roll pipe that is commonly available in 50' or 100' rolls and can be obtained in 250' rolls by special order. This means that for most residential applications we can run the entire run with one continuous length of pipe, and given that they are both a flexible roll material you will not need any fittings to make a change in direction. thus negating the possibility of an underground fitting failing.

The material cost is about the same, although the price advantage definitly goes to PE pipe, plus the fittings for PE pipe are considerably cheaper.

From personal experience my preference would be for PE Pipe. When I was a kid on the farm back in 1960 we ran a 250' line from our spring to the pump at the house, then another 400' line to our barn with PE pipe. That same pipe is still in service today and pumps hundreds upon hundreds of gallons to provide water for over 50 head of milk cows.

Installing both the PE and PEX is simple also. They make trenching machine that looks like a huge chain saw blade on the back of a small tractor and some of those machines have a roll pipe attachment. To install the water service they begin by digging a hole where your line enters the house large enough for a man to reach the pipe to make final connection, then the trencher digs a 6" wide trench and lays the pipe in the trench as it moves forward. When the reach the far end they have to dig another hole so the man can make the final connection to your meter, and the trenching machine then goes back and uses a small bulldozer type blade to push the dirt back in the trench. It is a very minimal invasion into your landscaping, and when done in this manner the whole job generally takes about 4 hrs or less.

[bubblegummom]

Wow, LazyPup! Very, very helpful and informational! With pex and PE do they have to be in some kind of a conduit to keep them from being smooshed?

We have a water leak and it's not obvious to us where it is. I'm just thinking ahead that the plumber may find we need a new pipe. But to complicate things, we're pretty sure the pipe is underneath the driveway.

[pushkins]

PEX and PE are direct buried, meaning that they are laid directly in the ground and cover up with earth.
There are ways the plumber can pull a new line under your driveway without cutting it up, a lot will depend on just how deep the line needs to be buried, freeze depth for example.

[LazyPup]

All the pipe materials that are listed as approved for "Supply Pipe" are approved for direct burial.

Having said that, code also states that in areas with rocky soil the pipe should be bedded with sand, then either sand or clean backfill until the pipe is covered one foot, then you may put the original soil back in the trench.

Minimum burial depth is 1' or 6" below your frost depth, whichever is deeper.

You stated that you think your existing water line may go under your driveway. As Pushkns mentioned above there are methods of running a line under the driveway with cutting the paving materials, on the other hand, you do not necessarily have to follow the same path as the existing water line either. You may be able to reroute the line in another location so that it will go around the driveway, the only caveate here is that as you increase the length of the line you also increase the pressure losses due to pipe wall friction.

Having now brought up the topic of "Friction Head Loss" in the pipe, we should also remember that 3/4" is the minimum diameter of line approved for residential water supply. In years past it was common to just use 3/4" on nearly all residential applications, but as lifestyles have changed over the years, we have added additional loads. By example, years ago most houses only had one simple bathroom, tub, lavatory and water closet, but in todays lifestyle we have often added additional bathrooms, showers & tubs, two or more lavatories, perhaps both a laundry sink & washer connection, and a dishwasher.

Before you replace the line, now would be an excellant time to determine what your actual load is and select the appropriate size of pipe to meet your load and compensate for Friction head loss.

If you will give us a list of how many fixtures you have connected to your water supply and the approximate length of your water line from the street to the house, I will be glad to compute the correct size of line for you.

Keep in mind that the pipe itself is relatively cheap, it is the installation that is expensive. By example a 100' roll or 3/4" PE pipe is about $50, but if you were to upgrade to 1" the pipe price would only be about $75.

There are a couple other topics that I feel I should mention here as well.

BEFORE YOU COMMENCE ANY DIGGING you should call "Dig Safe" (may be known by another name in your region). You should call dig safe about 5 working days before you commence digging and they will in turn notify all the utility companies to come out and mark the location of their underground lines to insure you do not damage their lines while doing your project. Don't take this lightly, it is the law, and you could be held both civilly & criminally liable for any damages if you happen to hit one of their lines. Dig safe is a free service that is actually paid for by the utility companies. If you can't find the number in your phone book under the heading "Dig Safe" you could call your water service provider, gas provider or any plumber or electrician and tell them your looking for the phone number to get the utility lines marked and they will be glad to give you the name of the service in your area and the number.

When you install your new line, I would strongly advise that you get a roll of the 4" wide yellow marking tape that is printed "water Line" and as you backfill the trench lay a strip of that plastic tape in the trench about a foot above the pipe. In that manner, if someone should happen to be digging a trench or even digging a hole to plant a tree or shrub the tape would warn them that they are close to your water line.

Although not required and certainly not commonly done on water lines, I like to also lay a "trace wire" which is simply a piece of awg14 green coated THHN wire in the trench with the pipe. You then just wrap the end of the wire around the exposed pipe on both ends. The wire serves no day to day purpose, but should you need to locate the pipe in future they can attach a signal injector on the wire and they use a device that looks like a metal detector to trace the actual run of the pipe without any digging. Trace wires are required on plastic gas lines, but copper wire is much cheaper than digging so I like to also place trace wires over water & sewer lines.

[bubblegummom]

Thank you, Pushkins! Here in Seattle we do have a few day cold spell or two in the winter.

[bubblegummom]

Thank you for all the excellent information, LazyPup! A lot to think about. If they put a larger pipe going into the house, though, wouldn't that be hard on our poor old house pipes?

[LazyPup]

Quote;"If they put a larger pipe going into the house, though, wouldn't that be hard on our poor old house pipes?"

The simple answer is NO, but in order to help you understand let us discuss "pressure" a bit.

Per code, when we install a new water system we must insure that the "static head pressure" at the "main water shutoff valve" in the house is a minimum of 40psi. (If less than 40psi we have to install a boost pump) while on the other hand, if the static head pressure exceeds 85psi we have to install a "Pressure Reducing Valve-PRV" to limit the pressure to a maximum of 85psi. Most people assume that the static head pressure will remain constant throughout the house under all conditions, but that is not true. Static head pressure is measured when all the faucets and demands throughout the house are off, and no flow is occuring. When flow begins we are instantly confronted with two factors, "VSHP Vertical Static Head Pressure" and "Friction head pressure".

Vertical static head pressure is the physical weight of the water, which is equal to 0.434psi per foot of vertical rise. By example, imagine a house where the water line enters the basement near the floor and your bathroom is on the first floor. Now let us assume an 8' rise from the main water line up to the first floor, and your shower head is at the code standard of 72" above the drain, so lets just say 72" above the floor. When you turn your shower on the water has to rise 14' vertically before it reaches your shower head so the amount of energy required to physically lift the water up to your shower head defined as vertical static head loss is 14' x 0.434psi/ft = 6.076psi loss and if that shower was in a bathroom on the second floor it would be another 10' vertical rise for a total pressure loss of 24' x 0.434psi= 10.416psi.

Now Vertical static head loss is a constant and therefore it is relatively easy to compute, but "Friction Head Loss" is an extremely elusive beast to deal with. As the water flows through the pipe there is friction between the water and the inner pipe wall and as the velocity of flow increases the friction head loss increases exponentially. By example, in a 3/4" plastic pipe with a volume of flow of 5gpm the friction head loss is 5.73psi per 100ft of pipe, but if the flow is increased to 10gpm the friction head loss jumps up to 20psi and at 20gpm the friction head loss would be 72.34psi. You must also keep in mind that the source of water pressure in your house is from the municipal main, and the friction head loss occurs through the entire length of pipe from the municipal main to the point of demand.

Now, while the friction head loss in a 3/4" pipe with a 20gpm flow was 72psi/100ft if the line size was increased to 1" the loss would only be 21psi and with an 1-1/4" line the loss would be down to 5.59psi.

Now 20gpm may seem like a lot of water, but a simple home with one bathroom (tub/shwr, lav, WC), kitchen sink & dishwasher, laundry and one outside hose bibb has total combined load in excess of 21gpm.

As a Plumber, when we design your supply & distribution system we are required to begin by computing the total demand load for your house, We then compute the total developed length from the source (municipal main) to the most distant fixture and we consult a "Friction head loss" table to determine the correct size of line for your house.

It should also be noted that the friction head loss tables also list the velocity of flow at each volume. In order to insure that you do not have excessive pipe wall errosion from the friction the code also limits the velocity of flow to a maximum of 8ft/sec in copper pipes and 12ft/sec in plastic pipes.

So now getting back to my previous statement, If you could give me a list of all the fixtures in your house and the approximate length of the line from the street main to your house, I would be glad to work up the total demand and let you know the correct size of pipe.

[bubblegummom]

LazyPup,

I tied the end of a ball of twine to the spigot where I think the line enters the house and rolled it out until I got to the water meter in the parking strip, then measured the twine. It was 54 feet.

Upstairs: sink, toilet, bathtub with no shower

Main Floor: sink, dishwasher

Basement: sink, toilet, shower, washing machine, concrete-basined sink next to the washing machine, and also a sink that has been non-functional since we moved in and probably never will be.

Outside: one working faucet, one non-working faucet.

Is there a meter or something that can detect a leak?

Can metal pipes be located underground by means of some kind of metal detector?

[LazyPup]

I am not sure which code is in effect where you live, but it really doesn't matter much because even though the IRC & UPC have some slight differences here, in essence they both work out to the same answer.

For the purpose of this illustration I used the IRC (International Residential Code) table IRC-T-2903

2nd Floor
Lav.............. 2gpm
Tub.............. 4gpm
W.C.............. 3gpm

1st Floor
Kitchen sink.....2.5gpm
D.W................2.75gpm

BSMT
Lav.................2gpm
Shwr...............3gpm
W.C.................3gpm

Laundry tub...... 4gpm
W.M................ 3gpm

EXTERIOR
(2) hose bibbs.....5gpm x 2 = 10gpm (We have to assume that you will eventually repair the non-working valve).

TOTAL LOAD .. 39.25GPM

We then consult a "Friction head loss table".

The Friction head loss table jumps from 35psi to 40psi so we would round your total off to the closest number on the chart, which in this case is 40gpm.

For a 1" plastic pipe @ 40gpm the velocity of flow is 15.41ft/sec and the friction head pressure loss is 34.33psi/100 ft (0.3433psi/ft x 54ft = 18.53psi loss from the meter to the house.)

For an 1-1/4" plastic pipe the velocity of flow is 8.82ft/sec and the Friction head pressure loss is 8.84psi/100ft (0.0884psi/ft x 54ft = 4.77psi loss.)

As you can see, the velocity of flow in a 1" line is 15.41ft/sec which is well above the code mandated maximum of 12ft/sec in a plastic pipe adn with an 18.53psi loss the static head pressure in the municipal main would have to be above 58.53psi to insure you get the code minimum of 40psi at your house.

On the other hand, for about another $20 to $25 material cost you could upgrade to the 1-1/4" diameter line and only have about a 5psi loss in the worst case scenario. This means that you start a load of dishes in the DW and go jump in the shower, and even if hubby should happen to turn on a lawn sprinkler from one hose bibb and use a hose on the other to rinse the lawn mower or his car, you still will enjoy full pressure in your shower. I don't know about you, but in my estimation, when you pay the cost of the excavation and labor to install the new line, another $20 +/- isn't much when you weigh it against the end result.

[bubblegummom]

Thank you very much for your calculations, Lazypup! You must be a Plumbing Engineering professor!

[LazyPup]

Thats just part of the basic package thats required to become a Journeyman Plumber.

[HayZee518]

LAZYPUP, was the forum's authority on all things plumbing and plumbing related since his joining in around 2005. He took a short hiatus for about five years until he got his personal affairs in order and relocated from Ohio to Massachusetts. Lazypup or Richard [his proper name] is a great friend to me and the forum.

[bubblegummom]

So, if we were to have PE pipe put in, how would the house be grounded?

[HayZee518]

you would have to drive two copper clad steel grounding rods 5/8" diameter a full 8 feet long into the ground, spaced four feet apart. most electrical codes and utilities say to run a continuous loop of #4 stranded bare copper from the panel to the 1st and 2nd rod then back to the panel. terminate both at the neutral bus bar.