Pumping Water From A Lake

[gouda]

Hi TV people

I have looked and searched but can't find the info I need so was hoping to get some advice from some plumbing experts

Am planning to get my water supply from a man made reservoir/lake, basically a large hole dug out for landfill, size approx 60m x 30m x 10m deep, filled with water drained from nearby rice paddies.

I guess this setup is similar to a shallow well and there are no issues of getting permission as this is on family owned land

Here are some facts

(1)The distance from the water to the house is approx 60m and is single storey

(2)The water will not be used for drinking only showering, washing, etc .

(3)The top of the lake is 2m below the house and would require another 2m lift for the shower. Assuming the water level drops 2m in dry season the max head/suction lift will be roughly 6m

I have done some research having absolutely no clue about pumps before and came to the following solutions.

(A)

Use a manual submersible pump suspended 1 m below a raft about 2m from the bank to pump into a 1000L plastic storage tank, then a 2nd pump to a 500L pressure tank onto the house

The pump would be turned on once a day to top up the storage tank

I have seen some submerisble pumps in Tesco, which look like sump pumps , would they be able to do the job? or do I need a submersible well pump?

Also the power cable would need to be exteneded from about the 10m supplied on the Tesco pumps to 60m however am concerned about the safety issue of this, is there a problem?

I'm think of placing the cable in plastic piping/conduit from the house to the water.

Advantages: more energy efficient, don't need to prime, able to cope if water level drops more than 2m, can chlorinate the water in storage tank

disadvantages:manual, need a storage tank, requires 2nd pump

Use a onland automatic centrifugal pump 10m from the house with a 50m pipe run with a footvalve hanging 1m deep into the reservoir, pumping into a 500L pressure tank, using a filter between the reservoir and the pump.

Is the 50m suction run from the pump to the water a problem? i.e. will the pump be able to cope, there will need to be a 2m drop at some point before the lake

Advantages: automatic, short power cable length, 1 pump and no need for storage tank

I'm concerned about the water quality as the water is green and worried about any chemicals /pesticides the local farmers may have used, also dead things and other nasty lurgies in the water.

What filters should I use? i don't expect much sand/sediment as I'd be placing the suction end of the pump will be hangin 1m from the top of the water

Should I use a disk filter ? or slow sand filter? the series of cartridge filters? I suspect a combination of these at different places.

your advice and opinions appreciated..

[Crossy]

I would go for the submersible-on-a-raft option, no issues with stuck foot valves and pumps losing prime.

Pump 60m to a coarse particulate filter (get one of the cotton ones that can be washed) to take out the really crunchy bits then into your tank. Pressure pump from the tank to the house via a finer particulate filter and probably a carbon filter too (to remove or at least reduce any chemical nasties in the water).

I would add a very fine particulate filter to the bathroom / shower feed to keep out the bigger bugs as this is the point where the water may enter your body.

You will need to size the extension cable correctly to allow for volt-drop on that long run, let us know the power of the pump. The pump will also need protecting with an RCD (one can protect both pumps).

You can get float switches to activate your submersible. Our local electrical emporium have a two-float switch (Radar brand) which only switches on when the tank becomes depleted to say 50% full, it turns off when the tank is full.

Edited March 30, 2009 by Crossy

[gouda]

Thanks Crossy

I think i have seen a similar product to the Radar float switch in Tesco lotus but wasn't 100% sure what it was as the packaging was only in Thai

For the submersible way, i was planning to site the 1000L storage tank close to the house because up to 30m from the house the ground is concreted, then a 2m drop and after that 30m of soil. This would mean the Radar switch would have to connect to the pump about 55m away. I presume I could just extend the wires, is that correct?

I haven't chosen a pump yet so can't tell you the power rating, but Tesco have a range of about 6 which some are plastic and some are stainless steel. What material would be better for a pump that is submerged all the time,have only seen ss borehole pumps though.

I'll post power rating as soon as I've chosen the pump

You don't seem to recommend using a large pressure tank between the house and on land pump, any reason why?, i don't really want the on land pump to kick in every time a tap comes on though.

btw there is only Tesco, Makro,homemart nearby haven't seen any special pump shops.. so not even sure where i can get a large pressure tank yet..

ta

[gouda]

Hi Crossy and others

Have got to the stage where the electrics for the building are nearly due to be installed and I am planning on using a submersible pump rated at 400W, maybe a stainless steel one that I saw, although not sure if it have a ground pin in the plug supplied.

From the crossy wiring website, I used the cable size calculator which gave me a 1.5mm2 for a 70m run for twin and earth in conduit, as I entered 1600W as the Load value. I just wanted to double check this was correct.

a few other questions

(1) Am planning to use a consumer unit with a RCBO built in, will this be sufficient for protection for 2 pumps?

(2) Is the yellow plastic conduit from local Homemart sufficient for external use and protection from rodents, rain etc?

(3) Should I just cut off the plug supplied and use a choc block type connector , in a yellow junction box to make the extension to the 1.5mm cable?

(4) Should the 2 pumps (1 submersible to storage tank), 2nd onland 150W pump from tank to house be on a separate circuit or is it ok to be on an internal sockets circuit?

(5) can some one explain how the radar brand float switches connect to the pump, and if I can extend the wires from the storage tank to the submersible, possibly up to 60/70m as I'm not sure where the storage tank will be sited yet.

(6) Can I use a 2 core 1.5mm2 cable with a separate 1mm2 earth for the extension as am planning to use separate ground for the house wiring or is it better to use a cable 1x1.5mm/1mm cable with ground?

(7) just noticed is says ambient temperature of 30C on the calculator, the temperature currently during the daytime in direct sunlight (most days) is higher than 30C, I'd guess possibly 40C as its unbearable. The cable will be in plastic conduit and maybe under soil. Is the 1.5mm2 still adequate?

thanking you all in advance

[Crossy]

1.5 cable gives a 9% volt drop on startup which may be too much if your supply is low anyway. Check your supply, if it's less than 215V then use 2.5mm cable.

Use 2.5mm twin run in the black plastic tube available for the job (it has a red stripe), this stuff is intended for burying and should work out cheaper than the yellow, otherwise the yellow will be fine but should be painted or buried to protect if from UV.

If the pump requires a ground, put a stake at the pump to save running a ground cable (save $$).

To connect the pump put an outlet in a waterproof box and plug into it, or as you suggest a choc-block (still in a waterproff box of course).

The pumps should really be on their own circuit, but both can share one breaker.

For our calculations the ambient shouldn't matter, it's aimed at maximum ratings and we're worried about volt drop.

Hopefully the switch comes with instructions It switches the pump power directly, so your wiring should be

Breaker==>Radar==>Pump