Well Point Problems after 20 years

[Andover]

I have had a sand point that I use for lawn irrigation for over 20 years. It is hooked up to a 1 1/2 horse sprinkler pump and runs from 5 to 7 spinklers heads at a time. I used 1 1/4 pipe and it is down about 23 feet.

I have had no problems with the system in those 20 years. This year I am getting much less water out of the well than I have in years past. There is not enough water coming out to even pop up some of the spinkler heads. When I first put the well in I was told I should be able to put a garden hose down the well, run the water and no water should come back up. 20 years ago when I did this, no water came back up the pipe. The well would take as much water as I could put into it. This year water does come back up the pipe. I am not sure if my well has started to go dry or if the sand point is clogged. I was leaning toward the theory that the sand point has just become clogged or has started to fall apart after 20 years and that is why water comes back up the pipe when I run water down the pipe from the garden hose. It has no where to go because the screen is clogged or fallen apart.

How long does the average sand point last? Do they deteriorate over time?

I lowered a cotton string down the well with a weight on the end of it. When it hit bottom I pulled it up and had just over 3 feet of wet string, that tells me I am in 3 feet of water.

Any thoughts on if the sand point is clogged or the well is going dry. I have two neighbors one about 150 feet away who has a two inch sand point and his is working just fine.

Any thoughts or ideas on what may be wrong would be great.
Thanks.

[speedbump]

So your lifting water 20 feet. The water is at the top of the screen and a centrifugal pump can only lift water 25 feet max. These are not ideal stats.

The 20 years is a long time for a screen to go without plugging up. I'm sure that is most of the problem. I have seen them plug up in less than three years. It's all in the water quality.

Do a Google search for Nu-Well Tablets. They are made by Johnson screen. I have had good success with them in the past (30 years plus now) but they must be used correctly or they don't work at all.

I used to put them in the well one at a time so they didn't bridge in a joint. You want then in the screen. Then you must find a water source to keep washing past them to dissolve them and push the mix out into the aquifer where most of the plugged sand is. This takes hours. Overnight is better.

bob...

[Andover]

Thanks for the reply. I will check on the Nu-Well tablets or may just pull the point. After 20 years it may not have much life left in it. What do you think about my comment that the well should be able to take as much water as I can put into it with a garden hose. Is that an accurate statement? Any other thoughts on improving the amount of water I am getting considering I only have 3 feet of water and am pulling it 20 feet?

[speedbump]

You can pull it if you want or start another one. Pulling it isn't as easy as it sounds.

You can't change where the vein is or the water table, so your stuck with what you have there. On the garden hose trick. Yes it's true, a well will give at least as much as it will take, usually more.

bob...

[Andover]

I pulled this one up about 15 years ago when my very little kids filled the pipe with landscape rocks, and your right its not an easy task.

Thanks again for your thoughts.

[Andover]

I do have one more question. I have been reading alot about the size of the motor and how it relates to the amount of water it will pull up. I am currently using a 1 1/2 horse Wayne lawn sprinkler pump that is also almost 20 years old. Is 1 1/2 overkill, could I get the same results with a 1 horse or smaller? I'm about 23 feet down using 1 1/4 pipe.

[speedbump]

You can look at the curves on my website. The first one is the centrifugal curve and the second link is the jet curve. These probably can't be compared to a Wayne curve.

Since the centrifugal curve is an actual curve, you can convert pressure to head by multiplying the pressure desired by 2.3 then add the lift. It will get you very close.

[Wet_Boots]

A Wayne Lawn Sprinkler Pump is just another centrifugal pump with a name that gets them sales they don't deserve. For electricity consumption, you could do better with a jet pump.