well yield

[mpowrd]

Out here in the costal mountains of California (near Santa Cruz), our wells are almost all of the "low yield" type where you might get 10 gpm for a while, but they don't refill fast enough, so you need a storage tank with pressure pump as a buffer.

I concur with the replies that 5 gpm should be more than adequate for a family, but I'd go ahead and put in a 1500-2500 gal plastic tank and pressure pump so the well pump doesn't cycle so often. This also gives you 6-10 days of backup supply (at 250 gal per day) if you have a pump problem.

Good luck and just keep checking the tests so you feel good about removing your contingency.

 

[mike223]

MadRef,
The well is 225' deep, and I have no idea what the static level is. It was drilled last week, and while I was there for the 3 days it took for the major drilling I had to leave before it was complete. I got the final gpm and depth from the drilling co. on Tuesday. I do know that it has 169 feet of casing, of which the last 40' is perforated by approximately 600 one quarter inch by 1 1/2" slots. They hit rock at 165', and set the bottom 4 feet of casing in the rock using an air hammer. It is a 6 1/8" ID galvanized casing. I'm guessing, but I'd say that maybe the static level is somewhere around 160-165'? That would mean a water column of 60'. The driller told me that you have 1.5G/ft of water, so that would make 90G in the well at any one time. Like I said, I'm just guessing at all of this, hence the original query. You have all made me feel easier about the yield at any rate, and I thank you for that.

 

[MadReferee]

Drop a lightweight floatable rope down the casing until it contacts the water. Subtract that distance from 225 and you will have the static level. 1.5 g/ft is about right for a 6" hole. I would have gone deeper but then again, it's not my money. /forums/images/graemlins/blush.gif

 

[mike223]

I thought about going deeper as well, but the driller, who has been in business in the area for 50+ years, said that anything over 250-300 wouldn't hit anything until 1400-1600', which would be called a "Knox" hole, which would penetrate the Knox artesian aquifer. I asked about going to 300', but he said he was concerned about sulfur at that depth. I don't know. I have to go with expert local knowledge. At least it's producing-for now.

 

[Slamfire]

My well produces 3 gpm by estimate. It is 320' deep with the pump at 300'. The water normally stands at 80'. When the pump and tank were installed I had to run 2 garden hoses to clean out the system, that is drain the well. One hose will flow for at least an hour. We had to irrigate our garden one year. /forums/images/graemlins/wink.gif

 

[Tim_in_IA]

You'll have to trust the local driller in this instance or get a second opinion from another driller in the area. My well is 400' deep and the pump sits at about 300'. We get 10-20gpm at that depth and the water quality is excellent aside from a little mineral which is actually good.

It all depends on the extremely local geology you are dealing with.

 

[mike223]

I have good news, and it's not about car insurance. The final well yield has come to 7 GPM on the pump test, which was done two weeks after drilling. The static depth is 65', so I have approx 100 G of reserve capacity. The drilling company pump guy recommended a 1500G holding tank with another pump into the house., so a total of two pumps plus lines to the house when built. The cost of this pump/holding tank setup is approximately $5600, on top of the $4800 drilling cost. But $10,400 for a well beats $40,000 for county water all day long. The next step is to build a shop/apartment and move in. Thanks for all the input on my question, it was/is greatly appreciated.

 

[Ronbo]

Just for comparison, I am at 12 ft elevation and 40 miles from the gulf south of Houston. My well is 6 inches, 465 ft deep, flows 50gpm, and I disconnected my water softener as it is soft.

Ron

 

[Jimbrown]

I do not think you will have any problem. My well makes 25 gallon per min but I only pump it with a solar pump that pumps at most 2 gal per min. I pump into a 1500 gallon tank and from there to two pressure tanks. I water three horses plus the house and drip irrigation on the whole place plus a swimming pool.

 

[JJT]

Mike, At 7gpm I wouldn't bother with a tank and dual pumps. While I built the house we lived with 1gpm, with 100 gallons in the casing, without any other reserve. In 3.5 years we never ran out of water. The bank required 5gpm for 4 hours, so we drilled a new well. Between the 2 wells we barely passed the test. We've been in the house for 8 years with no water issues and no extra tanks and plumbing. I rarely water the lawn or wash the cars at home, but when I have I've never run out of water.