Tuesday, October 27, 2015

How to Install a Frost Free Hydrant

As I mentioned yesterday, hydrants generally fail for two reasons:
  1. they aren't buried deep enough
  2. they have insufficient drainage underground.
The way that hydrants work is that the shut-off valve is at the bottom of the pipe.  It is plunger type valve that is opened and closed by a long rod that runs down the inside of the pipe.  When you pull the handle up, the plunger is pulled up by that rod and the valve opens.  When you push the handle down, the plunger seals and shuts the water off.

Just above that plunger is a small drain hole in the pipe. The same plunger that opens and closes the valve, simultaneously opens or closes the drain.  When the water is running the drain is blocked and when the hydrant is shut off, that drain hole opens.  Any water in the pipe drains out of that hole via gravity.

A properly working hydrant should never have water in the pipe except when actually in use.  I often see people wrapping insulation around their hydrants.  While insulating the pipe may seem like the thing to do, it is generally a waste of time because the pipe should not have water in it.  

If you do have water remaining in the pipe after the hydrant is shut off, you have a problem.  If your hydrant is working correctly and you still have trouble with it freezing, the problem is in the ground, not the pipe.  Placing a couple of hay bales around its base to keep the frost out of the ground is much more effective.

When installing a hydrant, it is crucial to protect the drain hole.  You don't want it getting clogged with dirt and if you have a lot of ground water, like I do, you want to give the water a place to drain to as well. 

You will need a backhoe or excavator to do this job unless you live in an area where there are no rocks and you can manage digging a deep hole by hand.  My property is NOT one of those places.  This little tractor backhoe was almost too small to deal with the rocks we have here.

A few of the things you will need are a hydrant, a plastic bucket with the bottom cut out, some clean, crushed stone, a bit of landscape fabric and whatever fittings are required for your size water line, which is typically 3/4 inch.  Border Collie supervision is optional.

The bottom of the hydrant needs to be below the frost line.  Plan for the absolute worst winter you can imagine and then go 6 inches deeper.  Do not let a contractor tell you that 3 feet is deep enough because he "never digs any deeper than that and besides, it never gets that cold around here anymore".

Measure the hole carefully to make sure that it really is deep enough.

Once you go as deep as you can (in this case, we hit bedrock at about 40 inches.  I would have liked this to be even deeper, but that would probably have required blasting.  It is 10-12 inches deeper than it was), put the bottom of the hydrant into the bucket before attaching the water pipe to it.  Once all the fittings are tight, make sure to turn the water on and test everything at this stage.  You sure don't want to find a leak after you've refilled the hole!

If you look really closely at the little brass nipple on the bottom of the pipe (at the white arrow), you can see water coming out.  That little brass bump sticking out is the drain hole that needs to be protected.

If you look close again, you can also see a bit of water in the bottom of this hole.  That is ground water seeping in.  It is what happens to every hole I dig up here.  It is why this job HAD to be done when it is dry and it is why I may still have problems with my hydrant even after all of this.  When it is wet, this hole would fill with water before you could finish digging it.

To help with drainage and to protect that pipe drain, fill the bucket and the area around it, with clean, crushed stone. 

In order to help keep silt from working its way down into the stone, cover it with the landscape fabric.

This next bit is optional and may be overkill, especially of you have gone deep enough and have good drainage.  Since neither is as good as I would like here and I had a piece of this blue-board foam insulation left over from another job, I put it over top of the fabric to help insulate the area and keep the frost out.  This may be a bit of paranoia, but I've found that, when it comes water lines, a little paranoia is not a bad thing.

Once you are sure everything works and is in place, back-fill the hole and tramp it down well.

To finish things off, it is good to securely anchor the above ground portion of pipe to a solid object.  There is a lot of leverage in a 7 foot pipe and even a small wiggle at the top can translate into damage down below.  If your hydrant isn't near a wall or strong fence, install a sturdy post alongside it when you bury it so that it will have solid support.

If you've done everything right, your hydrant should give you a lifetime of reliable water flow no matter the temperature.


  1. Let's just hope that the dang thing works correctly this winter and every winter!

    Don't forget....tomorrow is Scout's birthday!!!!

  2. wow. thanks for that lesson! I agree that you can never over do when it comes to drainage and water. d'Arcy says that Border Collie supervision is NEVER optional. .

  3. Please, do a "book" on everything from hooves, to hay, to valves. Your experiences are very valuable.

  4. Good post, would you insulate the pipe that comes up from the ground just for caution? We will probably have to replace ours soon too and I always wonder what it looked like 'down below'. We were lucky enough to have ours six feet deep.

  5. Ihave read several of these posts and only one said something about hooking it up to a water supply. I am an old lady and dense Is that supposed to be something Understood

  6. It does have to be hooked up to a water line. The black plastic pipe that you can see in several of the photos is the water line. This line runs underground to my house where it is attached to my pressure tank. I have a well so I have a pressure tank. If you have city water, the lines will be different, but the principle is the same. The water supply is attached to the bottom of the hydrant.

  7. Thank you so much. This was very helpful.

  8. I appreciate everything you have added to my knowledge base.Admiring the time and effort you put into your blog and detailed information you offer.Thanks.
    Robinets de Lavabo

  9. Have you heard of the "Never Dig" hydrant sleeve? It can be seen here http://fishermanufacturing.com/

  10. Do yo have any suggestions as to what to do when the water table rises above the drainage hole (that is our issue...by the time winter arrives the ground water is within a foot of the surface around here). As the drain hole is essentially submerged, the surrounding pressure does not allow the hydrant to drain.