Freeze less hydrant

I am putting in a few freezeless hydrants.  How much gravel should I put in under them for drainage?

Only half joking to say "The more, the better.."....?

Frost depth here is 5-6 ft and it's not too enjoyable to have to dig up for repairs.  With our heavy clay soils, I would not settle for less than a 3 X 3 X 3 ft dimension space below the weep hole on the hydrant with that space filled with loose gravel.  But I can't say what would be recommended by most installers.

depending on soil compassion at bottom of hole. if its like clay you want to have a bunch of rock and stuff that will drain , I would be tempted to say at least 2  5 gallon buckets or more of crushed rock or gravel if its like sand or gravel that is at bottom of hole your good. when you shut off a frost proof hydrant all the water from the pipe and any hose connected will drain back into the bottom of hole.

Yes, I am dealing with clay.  Fortunately the frost line is 18 to 20 inches.  I currently have the holes at 26 inches.  I assume the drain  hole needs to be below the frost line.  I will be using pea gravel.

Hi John,

On the net, you tube talks about inches of gravel.  Yes, I am skeptical.   Even with the good sense to disconnect a hose, I have to consider the hydrant turned on and shut off  several times.  I have water to the barn I put in earlier, but drainage was not an issue there.  Now I am trying to run water to three paddocks.  

John, two things I did:: (one good? one annoying?)
I put some landscape fabric as a filter around my gravel (we've got fine sand) to keep the sand out (for a while at least?) and it was maybe 2-3 60# sacks of gravel that I used.
I dug a small hole, which for me at 4' down for the valve + gravel below, made my fabric idea difficult to implement. I was also digging inside/near the corner of an already erected greenhouse, so space and headroom were issues as well...

For these kinds of things, I figure it doesn't hurt to over-kill with the recommendations.   There is no 'down-side' that I can see to adding more gravel or pea rock except for a bit of extra expense and time NOW for peace of mind LATER.   It's not just that you may have to dig up the hydrant if it's not draining properly, it's that Murphy's Law will come into play here.   The times that our hydrant has frozen up because the riser pipe is not draining properly is typically mid-winter when a block of days below zero F. have finally locked things up.....and there is no option to excavate.  When this happens, the ground surrounding the pipe, frozen as it is for several months to follow, does not allow for that pipe to thaw in any way, shape, or form.  So we need to wait until Spring works its magic and we can use the hydrant once again.   Good luck on the project, JD.....

Just as an assist for anyone else reading this, 2 cubic ft holds about 15 gallons.  In my clay soil, it takes about 24 hours for this much water to be absorbed.  Now, the question in my mind is what about repeated uses?   And, of course, a 2 cubic foot hole filled with gravel does not hold 2 cubic feet of water.   If the spot was on a raised area, I would consider installing a drain at the bottom of the hole.  

Optimistically, I see where 4 cubic feet might be desired to deal with repeated used of the hydrant throughout the day over a period of weeks.   Right now I am going to try to  calculate how much I expect each hydrant to be used.  

One additional thought that may help.  If you dig the trench to lay the water lines down and then dig deeper still for the gravel pit above which the hydrant will be placed, you may wish to bury the water lines first with gravel/pea rock and then finish the bury with fill/clay.  The idea here would be that the gravel along the water lines would serve as 'over-flow'  if your pit below the hydrant overfilled from repeated hydrant use.  If all of these lines are below frost line for your area, you would not need to worry about the overflow water freezing up around the water lines.  I hope this makes sense and that I'm not missing some engineering aspect.

Hi John W,


Great idea.  Of course, I am already doing that.  Yes, and I am digging the adjoining trench deeper near the hydrant. The deeper I go, the harder the clay seems to be.  So, digging 10 ft of trench 6 inches deeper is much easier than trying to go down an extra  2 ft at the hydrant, and gives be about 2.5 cubic feet more of space to hold the water ....that is in the neighborhood of an added  15+ gallons.