Are you thinking about installing a sprinkler system in your lawn this season? If so then there are lot of details having to do with sprinkler controllers, valves, and pop-up spray heads to consider but most importantly you need to get the depth right on your sprinkler pipes.
Trenching in the water lines to your sprinkler system should be done with care. Burying these pipes too close to the surface or too far underground can lead to problems down the road and possibly force you to reinstall your system all together.
Irrigation lines for residential sprinkler systems should be buried between 8 and 12 inches under the soil surface. Colder climates should be buried closer to 12 inches while warmer climates can be buried closer to 8 inches. Thinner lines should usually be buried slightly deeper to give them better protection from disturbances and cold weather.
Water lines should be dug to this depth to ensure that they remain undisturbed by normal surface activity, deep enough to be protected from freezing temps in the early Spring and late Fall, and shallow enough to easily supply water to sprinkler heads that rise above ground level.
Save yourself some time and trouble, read through this guide to know just how deep you need to bury your sprinkler pipes. I’ll even provide you with a few related helpful installation tips along the way.
Also, you may want to check this article out for more on keeping your outdoor water pressure as high as possible.
Preparations for Trenching a New Sprinkler System
Before you start to dig or even consider installing sprinkler piping, it’s a good idea to call your local maintenance or property people and have them mark out buried gas and water lines. By marking these ahead of time, you’ll avoid accidentally digging in areas where you can’t install anyway, and avoid causing damage to these lines with the sharp end of your shovel.
Once you’ve plotted out the route for your pipes, you should mark out the pipe route with some string that’s tied to sticks or similar tools in the ground. This will help keep your route even and on target and avoid digging off course and making a larger mess for yourself than you anticipated.
When you’re planning the pipeline, you should already know what sprinklers you’ll be purchasing and their accompanying watering zones. You should map these out to ensure that your pipeline plan accounts for the entirety of your yard. Poor planning in this sense can lead to you leaving some segment of your lawn out of the picture when it comes to watering, and this might force you to redo everything after the fact.
► See how sprinkler valves work here.
What is the Standard Pipe Depth?
Generally speaking, most pipes are set about 8 to 12 inches below your ground’s surface. This is far enough that disturbance is unlikely but close enough to allow the easy installation of sprinklers and other tools if necessary.
However, something to keep in mind when measuring your digging zones for yourself is that this number accounts for the top of the pipe to the surface of the soil. That is to say, the entire diameter is not accounted for in this estimation. Depending on your pipe size, you may need to add an inch or more to the digging depth to account for the bottom of your pipes.
For instance, if you dig to 8 inches but have a 2-inch diameter pipe, you’ll actually need to dig until 10 inches to accommodate the pipe in its entirety. You can easily measure the diameter of your pipe with a ruler or tape measure.
When you’re digging your trenches, be sure not to go too deep in some places and too shallow in others. Keep everything as level as you can; use a leveling tool if you have to in order to approximate evenness. Obviously, when it comes to the raw ground you won’t be able to get everything perfectly even all the way, but it should all be within a quarter of an inch or so. Use a smaller tool or your hands to sculpt the trench if necessary.
In addition, save all the dirt that you displace when digging the trench. This is stuff that you can use to recover the pipes once everything has been installed and it’ll save you time and energy when compared to scavenging dirt elsewhere to recover the trenches.
Deeper PVC = Better Cold Protection
You can go further than the recommended 8-10 inches if you live in an area which typically becomes freezing during winter months, or if you are otherwise at risk of a cold snap during other seasons.
In this case, burying your pipes further below ground, in the 10-12 inch range, is usually far enough that your pipes won’t freeze along with the ground above.
Keep in mind that the extra depth required by your pipes’ diameters still applies.
This is because aeration tools, which you’ll use to aerate your yard, don’t reach that far down. This keeps holes that allow oxygen and cold air into your soil far enough above your pipes that they shouldn’t suffer any cold damage if the temperature drops below freezing. In addition, 10-12 inches of depth is usually far enough to save your pipes from any shovel damage.
All of these depths are good for allowing optimal soil integrity and grass growth, as well. The pipes will be far enough down to not disturb any grass seeds or other small flowers that might take root in your yard. Anything shallower than 8 inches or so runs the risk of becoming damaged during winter or compromising your soil and preventing grass from growing properly.
What is the Typical Pipe Size for In-Ground Sprinklers
Most standard PVC pipes used for sprinkler systems have diameters between 1.5 and 2 inches. This is perfect for the above general depths that we recommended. When it comes to your sprinkler system and choosing between sizes, keep in mind that the diameter effects the overall water flow of your sprinkler system.
You’ll need a wider pipe for more sprinklers in a given yard since wider pipes allow more water through at sufficient pressure. More narrow pipes can certainly provide enough pressure for more sprinkler systems, but they’ll be able to service fewer sprinkler units at once.
This means that, in general, larger yards will require deeper trenches as a result of their needing wider pipes. By contrast, smaller yards will need shallower trenches since their pipes will also be smaller.
What About Sprinkler Size?
Account for your sprinkler’s sizes when digging your trenches. It’s possible that their depth might shave off an inch or two out of the depth necessary in the trench. You can even choose sprinkler types specifically for their depth if you have a yard in a cold climate that requires deep digging.
Pop-Up Sprinkers: What Depths they Need
There are two basic kinds of sprinklers: pop-up and stationary. Stationary sprinklers are always above ground and remain where they are all the time. Pop-up sprinklers, on the other hand, will dart into the ground when they’re not in use, only emerging when it’s time to water your lawn.
These have several great advantages. For one, they aren’t likely to be hurt by children, dogs, or the environment since they’ll be protected whenever they’re not spouting water. For another, they won’t be a tripping hazard for you or your family as you go through your hard.
However, you should keep in mind whether or not you’ll be purchasing these sprinklers while you’re doing your digging. This is because you’ll want to make sure that your given sprinkler pop-up heads are at the right length for the depth of your pipe trench.
Some pop-up sprinklers can only reach to 8 or 9 inches below the ground, while others can go all the way to 12. No one type is better than the other; the key is making sure that you match your chosen sprinkler head with the depth of your trench. Nothing would be more unfortunate than accidentally digging too deep for your sprinkler head so that it can’t emerge from the ground to water your lawn.
Pop-up sprinklers typically rely on riser attachments to accomplish their unique sheltering method and rise to water your lawn at the same time. You can buy riser attachments at varying lengths, and it’s possible to replace a riser unit if you’re already purchased a sprinkler set that is at a depth that’s unsuitable for your lawn.
In this case, you’ll just need to find the right size riser attachments and replace each of your sprinklers individually. This can still be time-consuming, but it’s far better than reburying an entire network of sprinkler PVC pipes.
The Best Tools for Digging a Sprinkler Trench
Digging as deep as we recommend might be difficult depending on the thickness and toughness of your lawn or ground. Some ground is so hard that digging through it with a normal shovel might seem impossible.
In this case, it’s often a good idea to water the area beforehand for an hour or so a couple of days before the actual digging starts. This gives the ground enough opportunity to soak up the water you’ve provided and softens the soil down to a reasonable depth. When you finally arrive to put your shovel to the test, you might find that it’s a lot easier to dig beneath the tough surface than it was before.
For small projects, standard shovels will work fine. You’ll want to have a hand spade or similar tool for getting in deeper without tearing a hole too wide in your yard. In addition, a small hand spade will give you some fine control to carve a narrow pathway in your lawn that’s the perfect size for placing sprinkler pipes.
If you don’t have one at least consider buying a trench shovel, they make this job so much easier than using a full size shovel or a small hand spade!
For larger lawns and projects, you might consider renting a trenching machine that can do a lot of digging work in short order. Fortunately, many gardening and home improvement stores have these machines available to rent all throughout the year.
Safety Tip
If you’re doing your digging by hand and are getting dirty in the trenches, we’d recommend using a breathing mask or at least watering the trench every so often to settle the dirt. Dirt will fly into the air frequently as you dig and breathing too must dust in a short amount of time can cause lung damage and potential medical issues.
Even something as simple as a paper mask can help alleviate this condition somewhat. Watering the dirt lightly with a hose can settle dirt in just a few moments, and it might make your digging easier at the same time. However, you don’t want to use so much water as to make the dirt muddy, as this can affect the stability of the trench and mess with your evenness across the length.
After Digging
Don’t rebury your pipes once you’ve dug the trenches and installed everything properly. You need to make sure that it all works before you replace the dirt you’ve unsettled. You’ll save yourself a lot of time and energy if you test the sprinkler system beforehand. This lets you see where any potential issues are arising from and take care of them before you replace the dirt and close everything off for good.
Conclusion
As you can see, digging pipes for your sprinklers isn’t too difficult once you know how deep you have to go and how best to accomplish the digging. With the right planning and effort, you’ll be well on your way to a functioning, efficient sprinkler system in no time at all.
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