Water Wells and pump technology

[turgid]

Helping a friend with a house renovation in Laos and one of the things that needs to be replaced is the water well and pump.

As I understand it currently they drill a hole 40 Metres deeps and then put a 40M,  6CM dia UPVC pipe in the hole which fills from the bottom and makes a skinny well.  Surface pumps can't suck more than 10 metres vertically  in ideal conditions.  So put a smaller bore UPVC in the well, seal the top and surface pump the water out into a tank either at ground level or on a tower.    Then either gravity feed or pump the water into the house.  So you are consuming 40 Metre "quality" water pumped from 5 metres assuming the pipe isn't cracked and there is no contamination from the top.   

 

A lot of this stuff seems to be done because they've always done it that way.  Are there best practices ?   I assume the conditions are similar in Issan. Anyone have any experience tips guidance on this. Is 40M enough ?  I've seen some UN guidelines that says a water should be a minimum 30 metres away from contaminants so that may be the reason for 40M given the animal and human waste on the surface.    Is there any advantage to using a submersible pump at the bottom instead of a surface pump? They solve the suck problem and I've seen them in Thai Watsadu but haven't seen anyone using them.  

[Artisi]

Well depth is based mainly on the availability of quality water, depths vary depending on location. 

Pumps for over 7/8 metres are either electric submersible pumps , line shaft driven submersible pumps (would be very rare in this part of the world for domestic supply)  or deep eductor pumps driven by high pressure water from ground level, effective but not very efficient in terms of power usage to water recovery. Check Google or similar for deep well eductor (or ejector) well pumps.

A good quality electric submersible is a good choice, Note good qualtiy - el cheapo will do the job - but for how long? 

Plenty of information out there if you search for it. 

Trust this helps. 

 

[Tweedle dee]

I did this on my plot out in the sticks about 15 years ago ..... water is plentiful but gone thru 2 pumps, only down side was water was a tad hard for the wifes shampoo. DUH .  TD

[grollies]

We've two drilled boreholes. One is 3" x 18m deep and is pumped from a surface-mounted pump, as far as I know this technology is fairly new here in Thailand although the principle is old news.

 

The other is a 6" borehole x 70m deep. Water is pumped from 1 1/2" submersible 1HP Franklin pump. Both work equally well. I quite like the surface pump set-up but the submersible has three times the capacity.

[KhunBENQ]

For this depth absolutely a submersible pump.

Our well is about 30 m deep and the the tank is about 8 m high.

Easily done with a "tiny" 3 inch submersible pump of 0.5 HP nominal (375 Watts).
The pump gives a high pressure of 6 bar with a relatively low flow/min.

(each pump can have a different characteristic, you have to check)

But exactly what I need for our domestic use.

 

I usually do not fill up the tank (2000 liters) to the top.

Just let the pump run for 20 min daily, gives about 500 liters.

Bought it at DoHome.

 

Edited December 26, 2018 by KhunBENQ

[impulse]

One caveat that bites some people in the butt.  The water level in your well may fluctuate wildly, depending on a number of factors including rainfall and withdrawals by others tapped into the same aquifer.  It may be artesian (flows on its own) today, and 10 meters deep during the dry season.

 

Don't install the pump based on your water level today.  Select and install it based on the lowest water level you can expect during the life of the pump.  And that can be as complicated as it sounds.  Best to get advice from someone who drills wells and installs pumps for a living.  Or at least nearby locals who have seen years of historical water levels.

 

[Artisi]

5 minutes ago, impulse said:

One caveat that bites some people in the butt.  The water level in your well may fluctuate wildly, depending on a number of factors including rainfall and withdrawals by others tapped into the same aquifer.  It may be artesian (flows on its own) today, and 10 meters deep during the dry season.

 

Don't install the pump based on your water level today.  Select and install it based on the lowest water level you can expect during the life of the pump.  And that can be as complicated as it sounds.  Best to get advice from someone who drills wells and installs pumps for a living.  Or at least nearby locals who have seen years of historical water levels.

 

Good advice. 

[sometimewoodworker]

13 hours ago, Artisi said:

Well depth is based mainly on the availability of quality water, depths vary depending on location. 

Pumps for over 7/8 metres are either electric submersible pumps , line shaft driven submersible pumps (would be very rare in this part of the world for domestic supply)  or deep eductor pumps driven by high pressure water from ground level, effective but not very efficient in terms of power usage to water recovery. Check Google or similar for deep well eductor (or ejector) well pumps.

A good quality electric submersible is a good choice, Note good qualtiy - el cheapo will do the job - but for how long? 

Plenty of information out there if you search for it. 

Trust this helps. 

 

Probably better to use the term "jet pump" for the surface mounted unit as an eductor is a water dredge usually powered by a jet pump. So searches for eductor are likely to less helpful.

 

Jet pumps easily available in Thailand can pump from 12 to 30 metres deep an example is the hitachi DT-P300GX series, the deeper you are pumping from the lower the flow rate, 12 metres 20 litres per minute, 30 metres 9 litres per minute 

 

A submersible pump can be a better option an example of drilling and using that kind is under

 

Submersible pump in well

 

Edited December 27, 2018 by sometimewoodworker

[Artisi]

6 hours ago, sometimewoodworker said:

Probably better to use the term "jet pump" for the surface mounted unit as an eductor is a water dredge usually powered by a jet pump. So searches for eductor are likely to less helpful.

 

Jet pumps easily available in Thailand can pump from 12 to 30 metres deep an example is the hitachi DT-P300GX series, the deeper you are pumping from the lower the flow rate, 12 metres 20 litres per minute, 30 metres 9 litres per minute 

 

A submersible pump can be a better option an example of drilling and using that kind is under

 

Submersible pump in well

 

Maybe I should have used the local jargon, but same same. 

Left hand image, twin pipe ejector /eductor /jet pump. 

[turgid]

Thanks for all the responses.  I didn't understand deep well jet pumps before .

This video may be useful to others understanding the technology.

 

So I have gleaned.

-  Shallow well jet pumps - if the water level never drops below     7 metres

-  Deep well jet pump       - if the water level never drops below   40 Metres

-  Submersibles up to 100 Metres

12 Litres of water reservoir per metre of pipe below the water level . 

We'll probably go submersible if i can get one  past customs, translation, consensus decision making, the local driller. 

 

This video also good although based on US measures and expertise.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

[KhunBENQ]

45 minutes ago, turgid said:

We'll probably go submersible if i can get one  past customs, translation, consensus decision making, the local driller.

Customs?

You really want to import a deep well pump?

All levels of quality and price available in Thailand, imported models from western countries too.

[Artisi]

16 minutes ago, KhunBENQ said:

Customs?

You really want to import a deep well pump?

All levels of quality and price available in Thailand, imported models from western countries too.

Correct, good quality available here. 

[sometimewoodworker]

8 hours ago, turgid said:

Thanks for all the responses.  I didn't understand deep well jet pumps before .

This video may be useful to others understanding the technology.

 

So I have gleaned.

-  Shallow well jet pumps - if the water level never drops below     7 metres

-  Deep well jet pump       - if the water level never drops below   40 Metres

-  Submersibles up to 100 Metres

12 Litres of water reservoir per metre of pipe below the water level . 

We'll probably go submersible if i can get one  past customs, translation, consensus decision making, the local driller. 

 

This video also good although based on US measures and expertise.

 

 

Your gleanings are mistaken.

 

regular (not jet) pumps have a maximum lift of 8 metres.

 

jet pumps have a maximum depth of 30 metres.

 

submersible pumps are as easy to buy here as the others, no limits, though you may need more than one if you go too deep.

 

There is never a need to build a reservoir unless you are supplying a village . The recommended water tank storage has nothing to do with the depth of the water table in metres or the amount of pipe. It is dependant on you water usage and reliability of you electrical supply. Some people don't have any water storage, personally we have several weeks, probably 2 months, without any water conservation, much more if we conserve.

 

Edited January 2, 2019 by sometimewoodworker

[Fruit Trader]

4 hours ago, sometimewoodworker said:

There is never a need to build a reservoir unless you are supplying a village . The recommended water tank storage has nothing to do with the depth of the water table in metres or the amount of pipe. It is dependant on you water usage and reliability of you electrical supply. Some people don't have any water storage, personally we have several weeks, probably 2 months, without any water conservation, much more if we conserve.

The OP makes reference to pipe capacity so I guess the reservoir (storage space) is within the bore between pump and water level.

 

Example :-

 

Bore depth 100M

Pump depth 55M

Water level 16M

Reservoir 39M

[sometimewoodworker]

10 hours ago, Fruit Trader said:

The OP makes reference to pipe capacity so I guess the reservoir (storage space) is within the bore between pump and water level.

 

Example :-

 

Bore depth 100M

Pump depth 55M

Water level 16M

Reservoir 39M

That makes more sense, but the poster was talking Litres not Metres so, maybe, he's showing a little more confusion

 

The referenced video is US centric and from a company that seems to want to sell jet pumps for every application.

Edited January 3, 2019 by sometimewoodworker

[Artisi]

15 hours ago, sometimewoodworker said:

Your gleanings are mistaken.

 

regular (not jet) pumps have a maximum lift of 8 metres.

 

jet pumps have a maximum depth of 30 metres.

 

submersible pumps are as easy to buy here as the others, no limits, though you may need more than one if you go too deep.

 

There is never a need to build a reservoir unless you are supplying a village . The recommended water tank storage has nothing to do with the depth of the water table in metres or the amount of pipe. It is dependant on you water usage and reliability of you electrical supply. Some people don't have any water storage, personally we have several weeks, probably 2 months, without any water conservation, much more if we conserve.

 

I responded earlier to the Max depth of 30M but don't see it being posted-- but the comment "was there really is no maximum depth that an ejector / eductor /jet pump can operate." 

Operating at greater depths requires careful engineering with many factors for consideration, well depth, standing water level at operating conditions, water quality, bore size. 

For commercial off-the-shelf pump units / local well driller, 30 - 50 M with a reasonably high water table could be considered a reasonable number for Thailand, but greater depths are within an eductors capability. 

[turgid]

The pump is being installed in Laos so Laos customs is the issue not Thai customs.

 

I was hoping in this era of Asean Thai Watsadu might be able to ship across the Mekong into Laos but they laughed when i asked about it. Also had no idea what a jet pump is

 

The reservoir mentioned is the height of the water above the pump in the well "pipe". One of the videos makes reference to the fact that pumping capacity can temporaily exceed the inflow into the well and you have no real way to know  that without running a year round test well.  Putting the pump several metres below the water line prevents the pump running dry.

For a surface pump 8 metres is the absolute maximum at Sea Level as i understand it. 7 metres allows a bit for raising the pump above ground level and wear.

 

[sometimewoodworker]

9 hours ago, Artisi said:

I responded earlier to the Max depth of 30M but don't see it being posted-- but the comment "was there really is no maximum depth that an ejector / eductor /jet pump can operate." 

Operating at greater depths requires careful engineering with many factors for consideration, well depth, standing water level at operating conditions, water quality, bore size. 

For commercial off-the-shelf pump units / local well driller, 30 - 50 M with a reasonably high water table could be considered a reasonable number for Thailand, but greater depths are within an eductors capability. 

Well if you want a normal off the shelf jet pump in Thailand the the limit is 30 metres water depth and I don't think anyone would call 30 metres down a reasonably high water table. Any driller who is suggesting a 50 metre deep water table can be jet pumped is telling lies

 

if you want to pump from deeper than that you can not pump from the surface with normal domestic pumps. 

 

For deeper you have to go for submerge pumps and my comment of no limits applies to those.

 

Edited January 3, 2019 by sometimewoodworker

[Artisi]

2 hours ago, sometimewoodworker said:

Well if you want a normal off the shelf jet pump in Thailand the the limit is 30 metres water depth and I don't think anyone would call 30 metres down a reasonably high water table. Any driller who is suggesting a 50 metre deep water table can be jet pumped is telling lies

 

if you want to pump from deeper than that you can not pump from the surface with normal domestic pumps. 

 

For deeper you have to go for submerge pumps and my comment of no limits applies to those.

 

without spending too much time on searching for data, the attached should suffice regarding depths from which water can be readily pumped by ejector system, plus - 30 meter water table is reasonable high when compared to many pumped water tables throughout the world which are hundreds of meters deep.

 

Deep Well Jet Pumps.docx

[grollies]

One thing missing from this conversation is static head pressure and pipe grade.

 

If you are using PVC pipe your maximum depth is 135m for any borehole.

 

You should use 13.5 pipe in any case.

[Artisi]

53 minutes ago, grollies said:

One thing missing from this conversation is static head pressure and pipe grade.

 

If you are using PVC pipe your maximum depth is 135m for any borehole.

 

You should use 13.5 pipe in any case.

Think there is a lot missing from the conversation. 

[sometimewoodworker]

9 hours ago, Artisi said:

without spending too much time on searching for data, the attached should suffice regarding depths from which water can be readily pumped by ejector system, plus - 30 meter water table is reasonable high when compared to many pumped water tables throughout the world which are hundreds of meters deep.

 

Deep Well Jet Pumps.docx

With out bothering to read a document that is probably talking about industrial, commercial or city water pumps.

 

 I am talking about domestic usage in Thailand.

 

30 metres would not be considered high, something like an aquifer that you may need to drill deep but then gives a water level of less than 10 metres would be considered high

 

Any driller who is telling you that you can use a domestic JET pump available in Thailand over 30 metres is wrong 

 

If you want to pay hundreds of thousands of Baht or millions I'm sure many things are possible. Most people here don't want to pay over 10,000 some will go over that (17,000 is my pump cost) few up to maybe 40,000 nobody I know will go much if any over that for domestic use.

 

compare apples to apples, show details of a domestic well pump in Thailand that goes to your claimed depth of over 50 metres and I will be happy to accept that I'm wrong, otherwise do stop wittering on about irrelevant information. 

Edited January 4, 2019 by sometimewoodworker

[sometimewoodworker]

54 minutes ago, grollies said:

One thing missing from this conversation is static head pressure and pipe grade.

 

If you are using PVC pipe your maximum depth is 135m for any borehole.

 

You should use 13.5 pipe in any case.

PP-R would also be a good/better option if you want to be sure of joints an/or go deep.

[Artisi]

25 minutes ago, sometimewoodworker said:

With out bothering to read a document that is probably talking about industrial, commercial or city water pumps.

 

 I am talking about domestic usage in Thailand.

 

30 metres would not be considered high, something like an aquifer that you may need to drill deep but then gives a water level of less than 10 metres would be considered higt

 

Any driller who is telling you tha you can use a domestic JET pump over 30 metres is wrong 

 

If you want to pay hundreds of thousands of Baht or millions I'm sure many things are possible. Most people here don't want to pay over 10,000 some will go over that (17,000 is my pump cost) few up to maybe 40,000 nobody I know will go much if any over that for domestic use.

 

compare apples to apples, show details of a domestic well pump in Thailand that goes to your claimed depth of over 50 metres and I will be happy to accept that I'm wrong, otherwise do stop wittering on about irrelevant information. 

The irrelevance is making statements that ejector pumps cannot operate any deeper than 30 metres together with other wrong information. 

It's a shame you didn't read the information, it was for standard off the shelf pumps - don't know if available in Thailand, the Davey unit could be. 

 

Edited January 4, 2019 by Artisi

[Artisi]

1 hour ago, grollies said:

One thing missing from this conversation is static head pressure and pipe grade.

 

If you are using PVC pipe your maximum depth is 135m for any borehole.

 

You should use 13.5 pipe in any case.

Bear in mind the static head is from the water level in the well to the discharge point, while the pump developed head is static head plus pipe friction losses plus any required discharge pressure needed. The depth below water level isn't part of the total head calculation. 

Main consideration for PVC pipe is mechanical strength if hanging a submersible pump from pipe. 

Edited January 4, 2019 by Artisi

[owl sees all]

23 minutes ago, Artisi said:

Main consideration for PVC pipe is mechanical strength if hanging a submersible pump from pipe. 

A submersible pump is not hanging from a PVC pipe. Nor is it hanging from the cable.

[bankruatsteve]

25 minutes ago, owl sees all said:

A submersible pump is not hanging from a PVC pipe. Nor is it hanging from the cable.

It is connected to both isn't it?  Is "hanging" a semantic issue, or what are you saying?

[Fruit Trader]

37 minutes ago, owl sees all said:

A submersible pump is not hanging from a PVC pipe. Nor is it hanging from the cable.

Picture of deep well pump installation where pump hangs from PVC pipe.

 

[owl sees all]

17 minutes ago, bankruatsteve said:

It is connected to both isn't it?  Is "hanging" a semantic issue, or what are you saying?

The PVC pipe stands on top of the pump. The cable is usually connected with cable ties, or similar, to the PVC pipe every couple of metres. Neither, the PVC, or the cable, take the weight of themselves or the pump. The submersible pump does not 'hang' in any way from the PVC or the cable.

Edited January 4, 2019 by owl sees all

[grollies]

25 minutes ago, bankruatsteve said:

It is connected to both isn't it?  Is "hanging" a semantic issue, or what are you saying?

My borehole has a very heavy Franklin submersible pump 50m depth in a 75m deep borehole. It certainly does not hang by the pipe nor the electric supply cable.