How We Designed Our Own DIY Irrigation System on a Well (Part 1 of 5)

Designing our own in-ground irrigation system! You guys, this is the post I have been wanting to write for almost a year. We just finished installing the front yard ourselves, and I am so relieved to know I am never going to drag a hose around in the morning again.

This is the first post in a 5-part series on how we designed, sourced, and installed our own in-ground sprinkler system on a well. Today is all about the design phase, which is the part most people get scared off by. The good news: if you can use a tape measure and do middle-school math, you can do this. Pour yourself something to drink and let’s walk through it.

How We Got Here (and Why I Was Done with the Hose)

We built our house and moved in last spring. Within a few weeks of moving in, a major heat wave hit and we lost basically every blade of grass in the front yard. The whole thing went brown and then dead. We had to re-till and re-seed the entire yard from scratch, and after all that work and money, I was not about to lose that grass a second time.

So all of last summer I was outside twice a day, dragging two hoses around the yard, checking every ten minutes that I wasn’t over- or under-watering, basically babysitting the lawn through the hottest months. It was a major pain in my butt and a serious time suck. Jacob set up a timer and a couple of moveable sprinkler heads to help, and I’ll be honest, I never quite got into the rhythm of using them right. The hose-and-stand-there method just became my whole summer.

Quick personal note while we are here: I was born without a right hand. Anything physical is harder and slower for me — most things take me about twice as long as they would take a two-handed person, and they are more taxing on my one good hand. So when I take on a project like this one, getting the design right the first time matters even more for me than it would for someone else. I really cannot afford to dig something up and re-route it. Anything I can think through before I am out there with a shovel saves my hand and my time. That is a big part of why I am starting this series with the design phase. It is the cheapest place to get smarter, and the most expensive place to be sloppy.

$10,000 and the Internet’s Reality Check

When we first looked into having a system installed by a commercial irrigation company, I made a Reel (Instagram / TikTok) where I tossed out $10,000 as the rough number a contractor would charge for a yard our size. Full honesty: I made that number up off the top of my head, spur of the moment. What I did not expect was the comments rolling in saying $10k was actually a good price, and that systems like this often quote out at $15k-$20k!

So even though we never got a formal written quote, the community basically did the price-checking for us. We had a real, validated cost ceiling.

Then we sat down and priced out the materials ourselves. Pipe, valves, sprinkler heads, manifold, controller. With a little legwork, the whole thing came in under $1,000. That is roughly nine grand in labor we would be “earning” by doing it ourselves. For us, that math wins almost every time.

The Two Numbers That Made This Whole Design Possible

Before you can size a single thing about your system, you have to know your water pressure and your flow rate. These two numbers are the foundation of every decision that follows: head choices, zone counts, runtime, all of it. You cannot design an irrigation system without them. Period, the end.

The good news is that you can get both numbers in about ten minutes with a $15 part from the hardware store and a 5-gallon bucket.

For pressure, I bought a basic pressure gauge that screws onto an outdoor spigot. They run about $10 to $15 at any hardware store. You screw it on, turn the spigot all the way open with no other water running anywhere in the house, and read the number. Ours read about 40 to 45 PSI, and as the photo says, the gauge I bought was cheap. Most residential systems land somewhere between 40 and 80 PSI. If you are under 40, you will need different head types or a pressure-boosting pump. Over 80, you will want a pressure regulator so your sprinkler heads don’t blow apart over time.

For flow rate (gallons per minute, or GPM), it is the bucket test, and it is exactly what it sounds like. Grab a 5-gallon bucket — the orange Lowe’s ones are perfect — open the same spigot all the way, and time how long it takes to fill the bucket exactly to 5 gallons. Then divide 300 by your time in seconds. That number is your GPM. If your bucket fills in 30 seconds, you have 10 GPM. If it fills in 48 seconds, you have 6.25 GPM, which is what we got.

One thing I would do differently, and this is a big one. I measured at our outdoor spigot, which is fed by a 1/2″ CPVC line in the basement. The actual irrigation supply line we ended up running is 3/4″ CPVC stepping into Schedule 40 PVC, and a 3/4″ line delivers significantly more GPM than a 1/2″ line at the same pressure. If you can, run your irrigation supply first, and then measure PSI and GPM right at that supply tap before you design your zones. We’re going to re-measure at the bigger supply before designing the backyard, and I bet the zone count out back ends up looking very different from the front. Don’t undersize your design to a spigot number you didn’t have to be stuck with.

A Quick Note for Anyone on Well Water

Most DIY irrigation guides quietly assume city water: unlimited supply, regulated pressure, a backflow preventer somewhere upstream that the city installed. We are on a private well and a septic system, so the calculus is different in a few ways. If you are on a well too, this section is for you. If you are on city water, you can skim and move on.

The first thing to know is that your well’s recovery rate matters as much as its peak flow. Recovery rate is how fast your well refills after water is drawn down. If you are running a high-demand zone for 20 minutes and your recovery is slower than your draw, your pressure tank will run dry and pressure will collapse mid-cycle. The cleanest way to find your number, especially for a new build, is to dig up your well driller’s log from your closing paperwork. The driller almost certainly tested and documented your sustained yield in GPM. If you cannot find the log, you can request a copy from the driller, or pull it from your county or state well-permit records. If the log is gone or the number is not on it, the homeowner version is a drawdown test: open multiple high-flow fixtures (a couple of outdoor spigots wide open) and let them run for 20 to 30 minutes while watching the pressure tank gauge. If the tank holds steady the whole time, your sustained flow is at least what you are drawing. If pressure starts dropping, the flow you were running just before the drop is your safe sustained number. For irrigation purposes, that is actually the more useful number than peak GPM.

The second thing — and this one took us a minute to work through — is that you do not want to short-cycle your well pump. Generic DIY guides tell you to leave a 25% buffer (design zones at 75% of your available GPM). On a well system, that buffer can actually work against you, because under-loading the line means the pump turns on, fills the tank quickly, shuts off, and short-cycles repeatedly during a watering. Frequent on-off cycling is harder on a well pump than running it continuously. So we made the call to design closer to 95% of our measured GPM (two 3 GPM Rain Bird rotors per zone on 6.25 GPM available) specifically so the pump runs steady through the cycle. The standard 75% buffer assumes city water and is solid advice when it applies. On a well, the math changes. Your pump’s owner’s manual will probably have a recommended minimum runtime per cycle, and it’s worth checking against your zone runtimes.

The third thing is to plan around your septic drain field. Drain fields are a no-dig zone. You cannot trench through them, you cannot compact the soil over them, and you really do not want irrigation lines crossing them. Pull up your septic install plan (or the as-built drawing from your well/septic contractor) before you sketch your zones, and route everything well clear of the field. Our drain field is in the backyard and well clear of the front-yard work, so it didn’t constrain Part 1, but it will be a real factor when we design the backyard zones.

And one more for the well-water crowd: heavy clay soil is its own design input. We have heavy clay around here, which absorbs water way slower than sandy or loamy soil. If you over-water on clay, you get pooling and runoff before the water has anywhere to go. The good news is that smart controllers handle this for you automatically. When we set up Rachio, there was a soil-type selector for each zone, and once you tell it you are on clay, it adjusts cycle and soak times for you (shorter watering bursts with rest periods between, instead of one long stretch). One less thing to math out by hand.

Mapping Out the Yard

This is the part of the project I actually loved. There is something so satisfying about pulling up Google Earth, screenshotting your lot from directly overhead, printing it out, and starting to draw on it. (You can also trace it onto graph paper if you’d rather work from a clean slate. Either way works.)

What you are after is a top-down map of every area you intend to water. On it, mark your property lines, the house footprint, the driveway and walkways, your lawn versus your garden beds, any established trees, your septic drain field and well head, any buried internet or utility lines, and anything you do not want hit by water — the AC unit, the side of the house, the propane tank, the mailbox.

For reference, our front yard is about 10,000 square feet of grass, with garden beds that wrap the foundation roughly 80 feet wide and 15 feet deep. The slope is gentle away from the house and steepens toward the front ditch. The beds are planted with hydrangeas, inkberry hollies, lambs ear, and a few other flowering varieties. There are also two trees out front getting watered by the lawn rotors, and we supplement them with a 30-minute deep soak from the hose every two weeks. Rachio actually recommended that approach during setup — the smart controller knows established trees need slower, deeper watering than turfgrass.

Once you have your map, the next step is to divide it into zones. A zone is just a group of sprinkler heads that all run at the same time off the same valve. We will get to how many zones you need in a minute. First we have to figure out what is going in the ground.

What’s Going in the Ground

Not every part of your yard wants the same kind of water. There are three main categories of head to choose from, and almost every yard ends up with a mix.

Rotary heads, or rotors, are for wide open lawn areas. They throw 15 to 30 feet, use less water per head (around 1.5 to 3 GPM each depending on the nozzle), and water slowly and deeply. Great for established turf. We went with Rain Bird rotors because they covered the front yard most evenly across the throw distances we needed.

Spray heads, or pop-ups, are for narrow strips, tight corners, and smaller lawn sections. They throw 5 to 15 feet, use more water per head (1.5 to 4 GPM each), and water faster. Use these where a rotor would be overkill or wouldn’t fit the area.

Drip lines are for garden beds, foundation plantings, and anywhere you don’t need overhead spray. Drip delivers water straight to the root zone and runs on gallons per hour instead of per minute, so it barely makes a dent in your GPM budget. We used Orbit 8-port drip manifolds in the foundation beds: one manifold feeds eight separate drip lines out to the plants.

For the front yard, we ended up with three zones total: two zones of rotors covering the lawn, and one zone of drip running the foundation beds.

The Math That Decides Your Zones

This is the part where the GPM number you measured earlier finally earns its keep.

The rule is simple: every head in a zone runs at the same time off the same valve, so the total GPM of all the heads in the zone has to fit inside your available GPM, with whatever buffer you are willing to live with.

The standard math most guides use is available GPM × 75% = your usable per-zone GPM. The 25% buffer covers friction loss in the pipes and gives you margin. Then you add up the GPM of every head you want in a zone and make sure it stays under that usable number.

Our actual math, with the well-pump tradeoff in mind, looked like this: 6.25 GPM × 95% ≈ 5.9 GPM per zone. Two 3-GPM Rain Bird rotors per rotor zone gets us to 6 GPM, which is right up against the limit and exactly where we wanted to be to keep the pump running continuously instead of cycling. The drip-manifold zone barely registers on the GPM budget at all. That is how we landed on three zones for the front: rotor zone 1, rotor zone 2, drip zone.

Bigger systems need more zones. The driver is your GPM, not your square footage. You can only push so much water through the line at one time, and the zone count is just how you split the system to stay inside that limit.

Routing the Pipe (and Why I’m Glad We Sketched It Twice)

Once you know your zones, you can route the pipe. Every system has the same basic anatomy: a main supply line running from your water source out to the valve manifold (the cluster of valves, one per zone, that turns each zone on and off, usually living in a buried valve box near the start of the system), and lateral lines running from each valve out to the heads in that zone. The main is pressurized all the time. The laterals are only pressurized when their zone is running.

We used anti-siphon valves for the manifold, which are mounted about 2 feet above the highest sprinkler head they control. That elevation lets gravity prevent dirty irrigation water from siphoning back into the supply when the valve closes.

We sketched our routing right onto the same yard map we already drew. Main line in one color, lateral lines for each zone in different colors. That sketch is what we handed to ourselves on installation day, and I cannot recommend the exercise enough. It forces you to make decisions that are otherwise easy to put off.

A few rules we followed: keep lateral runs as short as you reasonably can (less pipe means less friction loss means better head performance), don’t let zones cross each other if you can help it (it makes troubleshooting way easier later), and put the valve manifold somewhere you can actually get to. You will need to open it for repairs eventually.

The hardest part of the entire design phase, honestly, was just committing to a layout. Originally we had planned to run a supply line through the front so we could expand front zones later. We went back and forth on it for what felt like a week before I finally said “we have to pick one.” We abandoned that plan and grouped all the anti-siphon valves near where the supply line exits the house. The cost: we cannot easily expand front zones on the right side of the house from the front anymore. The benefit: simpler manifold, fewer trenches, less pipe. Future right-side coverage will come off the backyard supply when we run that. Sometimes the best version of a design is the one that is good enough and actually gets built.

The Two Pieces I’d Hire Out

Before we go any further, this is the one part of the project I would tell anyone to call a licensed plumber for. No exceptions, no winging it. Backflow prevention is what keeps irrigation water from contaminating your drinking water — especially serious on a well system, where there is no city safeguard upstream. The supply tap into the home’s main water line is regulated work in most areas. Both of those usually need a permit and a licensed plumber.

The rest of this project you can absolutely do yourself, but those two pieces are not the place to figure it out as you go. Check your local code, get the right people for those parts, and DIY the rest with confidence.

Picking the Brain (Your Controller)

The controller is the brain of the whole system. It tells each valve when to open and how long to run.

We went with Rachio. After comparing the smart controllers on the market, Rachio came back as the consensus pick from the research, and the logic for going with the nicer option was simple: the savings from doing the rest of the project ourselves bought us the better controller without changing the overall budget. That is one of my favorite things about DIY. The labor money you didn’t spend lets you buy quality where it actually matters.

A few things to think about when you’re picking yours. Stations — you want at least as many as you have zones, plus one or two extra for future expansion. Don’t buy a 4-station controller for a 4-zone system if you might add a drip zone later. Smart vs basic — smart controllers connect to WiFi, pull weather data, and skip a watering if rain is forecast. The water savings alone usually pay for the upgrade. Soil-type and plant-type setup is where Rachio really earned its keep for us. You set the soil type and the plants per zone, and the controller programs cycle and soak times accordingly, no spreadsheet required. Indoor vs outdoor mount is mostly a logistics call: indoor is cheaper but you need a power outlet and a way to run wire to the valve box; outdoor costs more but installs where the valves are.

Why We Built One Zone Above Ground First

Before we glued or buried a single thing, we built a temporary above-ground version of one zone. Pipe, rotors, a hose connection, and a manual valve standing in for the anti-siphon valve, no glue (the joints popped apart from pressure a few times, which was fine for a test). Turning it on let us confirm that the rotors actually threw the way we expected at our actual pressure, and that the spacing covered what we needed it to cover. If something hadn’t worked, we could have figured it out in an afternoon instead of after 80 feet of trench was already dug.

I cannot tell you how reassuring it was to stand back and watch that test zone water the grass exactly the way we’d hoped! If you do nothing else from this whole post, do this one thing for at least one zone before you commit to the buried, glued version.

A Few Things I’d Do Differently

Now that the front is in the ground and running, here are the things I would tell my past self at the start of the design phase.

Run the irrigation supply line outside first, and then measure PSI and GPM right there. Designing to a 1/2″ spigot’s flow rate when we were going to install a 3/4″ supply meant we under-built the front. We’re going to fix this for the back.

We probably could have gotten away with a smaller controller. Once we re-measure at the bigger supply, we may end up with fewer total zones than the controller has stations. Not the end of the world, but extra cost we did not need to spend.

Skip the delusion of hand-digging in our clay. Two hours just to remove the sod over one trench was the moment that plan died. Renting a trencher would have given us a whole weekend back. (Full trenching story is in Part 3.)

Tape and screw threaded fittings carefully the first time. We had to cut out and redo a couple of shutoff and check-valve connections that hadn’t been tightened enough. Cementing the master shutoff as a CPVC ball valve was the right call there: no risk of the cemented joint backing off.

Resources That Actually Helped

There was no single golden source on this one. We read and watched a LOT. Here are the three that earned their keep, in case you want to go deeper on any of them. Credit where credit is due, and if these turn out to be useful for you too, head over and give them a like or a follow so the people making this content know it’s working.

• How to Install a Sprinkler System | A DIY Guide (YouTube) — solid start-to-finish overview of a DIY sprinkler install. Useful for getting the big-picture sequence in your head before you start sketching your own design.
• Anti-Siphon vs Inline Valves (YouTube) — clarified when to use anti-siphon valves vs inline valves and how to position them, which directly informed our valve manifold setup.
• How to Install a Sprinkler System (Popular Mechanics) — solid technical reference for the procedural fundamentals on the install side.

One thing about the research process: even sources we didn’t love taught us something, sometimes just what not to do. If you have a friend or neighbor who has already installed an irrigation system, ask them first. That is faster than YouTube every single time. We did not have that, so we read until our brains were full and then we built the test zone above ground to fill in the rest.

What’s Coming in Parts 2 Through 5

Now that the design is down, here is what is next in the series.

• Part 2 — the full parts and materials list with every product, every link, every price.
• Part 3 — installation day(s): trenching, laying pipe, setting heads.
• Part 4 — wiring up the controller and getting Rachio programmed for your zones.
• Part 5 — maintenance and winterization, plus any updates after a full season of running it.

If you have been hand-watering all summer, or babysitting a dying lawn through a heat wave like I was, y’all, this part is the part most people back away from. Once you have these numbers and a sketch, you are past it. The rest is just labor.

Got questions on any of this? Drop them in the comments and I will answer what I can. Or hang tight for Parts 2 through 5, because there’s a real good chance it’s already covered there.

— Kara