To my understanding, it takes, on average, one hour for a standard sprinkler system to water the lawn 1" in depth (tell me if I'm wrong here). My lawn is nearly 7000 square feet with 9 stations of sprinkler heads. If I were to water 1 hour on each of those stations, do the math, that would take too long and too much water.

My Dad once set it to water 45 minutes on each station one time and subsequently paid an extremely high water bill. We are not looking to use tens of thousands of gallons of water each week, seems a bit wasteful if you ask me.

Am I correct in saying that it takes this much water to maintain a lawn of this size?

To figure this out you need to know your soil type (sand, silt, clay etc.) you also need to know how many gallons per minute your sprinkler heads deliver or thier nozzle size. Next you need to know how many pounds per square inch pressure you have in your water line and also if there are any pressure regulators or reducers built into your system and what thier rating is. A good system should have a regulator or reducer and it will likely be rated in gallons per minute - GPM, but could be rated in pounds per square inch - PSI. So if you tell me your soil type, psi ahead of any reducers, sprinkler head rating, how many heads there are and thier coverage area, the rating of any reducers, type of grass and its rooting depth we can get started. There are a few other considerations to really tweak a system but really not nescessary except for the peak evapotranspiration rate for your area. Sounds fun doesn't it. Oh, I almost forgot is your yard flat or sloped?

Alternatively you could just put some shallow containers around your yard and see how long it takes to get 1" of water in them. It takes more time, but it won't make your brain explode.

How often do you THINK you need to water? My next door neighbor has watered her front yard once this year and has not watered her backyard at all. It is as green as all the neighbors who water once a week or more. Just make sure you don't set your system to come on automatically...you be the judge and it shouldn't be that often.

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Sandi
Texas Certified Nursery Professional
Texas Master Naturalist
Organic gardener
Tree-Hugger
Native Texan

That's why having a kickin lawn is not so ecologically friendly afterall. Earlier in the summer, we have an extended drought here and the grass turned brown, that's how bad it was. I had tried to water it for about 30 minutes every other day and wound up with $100+ water bills. Then I stopped watering!

Here's some things I might suggest though, having researched or done them, a drought tolerant grass like bermuda might be an option. You also might consider alternate sources of water. I was able to put in a well, but I am in Florida and you don't have to go that deep here. Another option is to collect rain water and that best way I found to do that is by rain gutters and a special attachment to take the water that hits your roof and dump it in a large 150-500 gallon tank. You can put any connection on the tank you want and as long as you have a sprinkler valve, your sprinklers will run reliably with the rain water you collect. For me, If I was able to collect 10,000 gallons of rain water and use it all for irrigation, that's $200 saved. The big question is, how much water can you refill with if you're in a drought. That's why I went with a well. Incidently, I haven't used the well in months because its been raining so heavily here. Oh yeah and hurricane frances managed to somehow pick up the well pump and toss it several feet away and break the pipes.

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September 24, 2004 : Preparing for the second deadly hurricane to hit this area this month! I can't take much more of this.

That's unfortunate.

Gnalekim: I'm sad to say that most of the information regarding those technicalities was never given to us from the previous owner. We moved in over 7 years ago and I doubt they would know anything about it. Is there a way I can seek out the specifications you need?

I will tell you we have common bermuda grass in heavy black clay soil and our lawn if mostly flat.

You don't need all that stuff to figure out how much water to put on. Here's another way.

Fill a 30 gallon trash can with water from your biggest hose and time how long it takes. You get your flow rate from that. Let's say you have 10 gallons per minute flow. 10 gallons per minute is 600 gallons per hour. Then look at your garden size and flip over to Google. Type in the following: "1 inch times 7000 square feet in gallons" without the quotes. The answer will come back as: (1 inch) times 7 000 (square feet) = 4 363.63635 US gallons. So it takes 4,363 gallons to get 1 inch of water on it. Since you're on Google and possibly amazed that it can do the conversions for you, type in this: 4363 gallons divided by 600 gallons per hour in hours. The answer will come back: (4 363 US gallons) divided by (600 (US gallons per hour)) = 7.27166667 hours. So it would take you about 7 hours and 15 minutes to get an inch of water on your lawn.

If you really want to check out that Google feature, let's say you have a flow rate of 7.5 gallons per minute and want to skip the intermediate step of figuring out flow rate in gallons per hour. Type this: 4363 gallons divided by 7.5 gallons per minute in hours. The Google answer is: (4 363 US gallons) divided by (7.5 (US gallons per minute)) = 9.69555556 hours. Pretty cool!

By the way you cannot use any averages. Every house on your street will have different flow rates. As someone said, the soil type and grass type make a difference. My next door neighbor never watered her St Augustine lawn in 5 years and, drought or not, it always looked better than my lawn. If you are deep watering on an infrequent basis, you will develop roots that hardly ever need your irrigation.

_________________
David Hall
Moderator
Dirt Doctor Lawns Forum

David... the whole problem with this "Google math" method is that the flow rate from his garden hose is not going to be meaningfully comparable to the flow rate from his sprinkler heads.

The pipe layed could be one of a couple of different diameters. It's also going to be a bigger diameter coming off the main, then stepped down from there for distribution to the zones. The heads could be 10 or 15 GPM themselves... and not even the same from zone to zone. The screws in the heads could have been adjusted down to reduce the spray pattern, thereby changing their output also.

That's why the empty tuna can works so well -- you are measuring the actual output at each area.

Ziroth... FWIW, I get 1 inch of water in 25 minutes, from an adjusted 10 GPM Toro 360-spread pattern head. YMMV.

_________________
...Bill

I fell asleep just trying to read the post. Why go through something sooo convoluted for something so simple?

As with Sandih's neighbor I haven't mechanically watered my lawn yet this calendar year. I haven't had any significant browning. I view the phenomenon as one of the benefits or organic lawn care.

_________________
Keeping it clean and green here, Boss.
Reduce, Reuse, Recycle

Yup... and it also takes time away from making that tuna sandwich for lunch, eh?! David... relax and have lunch.

_________________
...Bill

If your easily bored ignore this post.

If your dead set in your ways again, ignore this post.

If your interested in my opinion please read on.

Plants require a certain amount of water to grow and survive. plant health, soil type and fertility, enviromental factors and acceptable moisture stress all play a roll in determining how much water to apply to a cultivated area to achieve the desired results. As I consider a lawn a cultivated area being manipulated to achieve a sense of gratification resulting from the elevated asthetic appeal of the cultivated area, real or percieved, I choose to do some figuring to maintain a certain amount of appeal. When fiquring how much water to apply you first must decide what level of appeal you want. Green in the spring, brown in the dead of summer then green again in fall requires the least water. A vivid green all year requires the most. Most everyone at this site will agree an organicly maintained lawn will be healthier and require less water than one that is chemically maintained so go organic first. After having gone organic with your lawn and deciding what level of appeal you want don't be afraid to do a little work to determine how much water to apply. Unfortunately, I have noticed sometimes what I would consider a bit too much of a fly by the seat of your pants wet finger the sky kind of attitude along with organics. If you choose to manipulate nature doing so organicly is a fine start but it doesn't change certain facts, such as: Plants transpire water at a given rate depending on plant type, plant health, above and below ground environmental conditions, soil and water salinity, etc. Soils hold a given amount of water between the fully saturated and available water points. Soils will accept and release water at a given rate depending on soil type, generally sandy soils are fastest and clay soils are slowest. Bla, bla, bla.

Averages as well as theoretical calculations are intented to provide a baseline or range or a place to start because it is recognized by everyone that conditions vary wildly all over the place but reasonable averages can sucsessfully be used as indicator of about what you should be doing.

Fiquring about how much water to apply is not sooo convoluted. From my home in Canada within 20 minutes I came up with this basic answer to that question.

http://texasweather.tamu.edu/homewatdue ... g&spread=7

Assuming Irving is close to ziroths location. I tried but I'm not that familiar with Texas. Just enter sun exposure, turf type (bermuda), effective rainfall and sprinkler rate.

I don't suggest you have to get rediculous so if you are missing too many pieces of info regarding your systems design I would go with ziggy and billusa99's suggestion of a tin can to determine the actual performance of your system, but I would do this test with maybe three zones operating at once with a can in each zone and run the zones for 1 hour then use a ruler to measure the water level. I doubt your system can properly handle firing all zones at once so don't bother. It may be a good idea to have your system assessed to determine its capabilities.

Try using the above link and modify the delivery rate fiqures. If I understand the workings of the above link properly the rest including all the bla, bla, bla, is done for you for your approximate location.

Use this as a baseline, I would actually start at about 75% of the suggested time, and go from there. I would also set your system to fire atomaticaly so that it comes on early in the morning and use the water budget feature to modify the cycle time base on current contitions or symply reset the actual time. Don't forget to decide how important it is to you to have green lawn all the time and go organic with it, it really works.

You could also just wait to water until you notice that the grass does not spring back up when you walk on it and you can see your last couple of foot steps. Seems to work for me That is a nice calculator on the TAMU site. I have increased the perculation rate of my turf at work by following the recomendations at the top of this forum. When I started, I could only water for 20 min's at a time before I got run off. Now I do not get run off in most areas except during very hard rains. The turf is actually better looking now than it was when I was watering for 20 min. every other day. Note, the recomended once a week watering is only during the hottest part of the summer, that is why I watch the grass to see when it needs water.

gnalekim...thanks for the comments and the link! Pretty cool site!

Irving is a NW suburb city of Dallas -- as North Van is to Van without the water in the way! And just like there, when it's pouring in one spot it can be dry in the other.

But, it is a great tool from the point of view of knowing what I have applied last week, or what has rained in my yard via a rain guage, so I can then use the rest of the tool to adjust accordingly!

Thanks again!

_________________
...Bill

gnalekim...You should be a moderator. The link does make a very good baseline. This is what I look for..Baselines. I think many people giving help forget about how much their environment (i.e., temperatures, humidity, and annual percipitation) can change everything. They should at least describe their own environment when giving help on issues such as irrigation, weed control, and so on.

Thank you!