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FAQs: Maintain Water Pressure with Irrigation Sprinklers on a Low Yield Well |
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Question: I have a well that works fine. But I had a sprinkler system installed and it drains the tank so fast that when it is running after about 5 minutes it will only hold at 20-25 psi until the sprinkler shuts off. What do I need to do? Answer: This is a common question. I notice that you did not say you run out of water, just that the pressure is terrible. The simple answer is that you are trying to get more water than the well pump can deliver. The pump simply hasn’t got enough power to push water fast enough to feed all of the outlets you are asking it to feed. There are three possible reasons for this.
A little background so you know why #3 is a real possibility: A well is simply a hole dug or drilled into the ground into which water pours, runs, leaks or dribbles, depending on local geology. The rate at which water runs into the well is its Yield. You cannot remove water from the well faster than it comes in for any length of time, without pumping it empty which will result in NO WATER coming from the sprinkler or anywhere else. If you are the original homeowner or if you have lived here for several years and there has been no noticeable change (degradation) in plumbing performance then I’d bet the yield of this well is inadequate to directly supply your sprinkler system. If you are new to the home, then any one of the three are a possibility. Why not just throw a bigger pump in the well? Because, if this is a low yield well, you will change the complaint from I have poor pressure TO I run out of water! When a well is constructed for a home, the hope is that it will provide enough water to feed all of the plumbing and possibly a landscape irrigation system. The well driller has done everything he can to make that happen but in the end he can only provide what nature has to offer. So what does one do when the well nature offers has a 2 gallon per minute yield but the house presents an 8 – 15 gpm need? If a pump large enough to feed the home were installed the family would run out of water and if the pump were sized for the well yield (2 gallons per minute) then you’d have a hard time taking a 3 gpm shower. The pump installer will most often choose a pump that will supply one bathroom – say a 5gpm pump – and rely on the water stored in the well to make up the difference between what you are using and what the well is producing. Example: You have a two gallon per minute well and a 5 gpm pump. The pump will provide a decent shower if you don’t use more than one bathroom at a time. For every minute you shower you use 1 more gallon than the well is producing. A 6” well contains 1.5 gallons of stored water for each foot of water in it. Therefore every minute you shower the well level goes down 2/3rds of a foot. A ten minute shower might draw the well down 6.66 feet. If other plumbing is also being used then the well level will fall a little faster. You are not likely to run out of water because the pump won’t provide enough pressure to use enough plumbing outlets for that to happen – which is also why the sprinkler isn’t running the well dry. If you have lived there long enough to know that plumbing performance has always been the same, indicating the likelihood that this well is inadequate for this use, you have 3 choices. Cease using the irrigation system. Drill another well – if the odds are good that you will find a yield adequate for your sprinkler system or install a Well Manager which offers a guaranteed result. How do you decide what to do? Try this: Have you ever discussed water with your neighbors? Are there other homes in the neighborhood that have sprinkler systems? Do any of them have poor pressure? Can they run two showers at the same time or turn on the washing machine while someone is in the shower? Have they been told by someone that there isn’t enough water in their well to run a sprinkler system? Did they have difficulty finding an adequate well when their home was built? Asking around can reveal a lot of information. If these answers confirm my suspicion, then we could work at this backwards. Knowing how many zones are in your system, how many heads are on each zone and the discharge rates of each head (marked on many heads as a decimal number 2.2, .75, 1.5 etc) it would be possible to calculate the amount of water required each day to operate the system, the pump size needed to properly run it, and the well yield required to directly supply it. The well yield requirement along with the information you find asking around can give you an idea as to the odds of being successful drilling a new well with a yield adequate to directly supply your system. The information on the irrigation system would allow us to tell you the minimum well yield required to run the system with a Well Manager and a simple well yield test will tell you whether your well is adequate. The yield required with a Well Manager® is only a fraction of that required to supply an irrigation system directly from the well so odds are that this will work. In any case, we can tell you up front whether or not we can solve your problem and exactly what performance you can expect before you pay a dime. Wouldn’t it be great to run the irrigation system and shower at the same time? A Well Manager® can provide enough water to do that. There is no other solution to this kind of problem that can guarantee a result before work is started!! |
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