Rainwater Harvesting - pumps etc

[Apache]

Plan is to collect rainwater in 6 X 1000l IBC containers, connected together (outside). A pipe then runs ~12m underground and then needs to rise 3m to fill a header tank.

The header tank is to feed a pressure washer - that can run off a ground level water-butt. 

What is the best way of moving the water? Some kind of pump controlled by a float switch - I assume?

Does pump want to be at ground level or up next to the header tank (my preferred location).

Looking for a suitable pump and switch - also interested in any thoughts or suggestions

Cheers

http://www.ebay.co.uk/itm/Inline-Water-Pump-Centrifugal-1-inch-BSP-Cast-Iron-IBC-Water-Pump-IBC-Fitting-/281134830013?hash=item4174f111bd:g:H9gAAOSwd4tUKoTu

Something like this?

 

[Sidewinder]

OK, a centrifugal pump cannot suck water.

It HAS to have a net positive suction head.

So you need to look at the locations and ensure that the pump basically has a flooded suction with a head behind it in simple terms.

 

[Andy™]

first thought is winter and the pipework / pump freezing

the pump would also need to be below the water its pumping unless its self-priming

 

[Sidewinder]

No they can't.

Yea cannae defy the laws of physics Captain.

They HAVE to have a net positive suction head, this is not quite as basic as it sounds, but, they can't suck, end of.

 

[Apache]

The IBC tanks will be outside and connected together with 25mm pipe.

A 20mm pipe is buried under the concrete.

The tank will be inside a shed on the roof of a lab - in an enclosed agricultural type shed - that is not bought as yet. so can be anything, but not massive or I'll have to put a lot of wood in the roof and lose head room.

The measurements in my OP are pretty damn accurate - from leaving the 25mm to 20mm the run will be no more than 15m - including the 3m vertical height.

The pressure washer uses 8.3lpm and is likely only to be used for a few minutes at a time. I just want the pump to keep the header tank topped up, not to pressurise or run all the time.

3 phase available in the shed.

 

[Sidewinder]

No they don't.

 

[Apache]

On the morning the concrete was coming I remembered I had forgotten to put a pipe in for this task - all I had was a roll of 20mm blue MDPE polypipe, so that is what I used.

 

[Apache]

Once we get onto the 20mm there will be 2 elbows.

The IBC containers will either have an elbow each or a T piece fitting. Stacked in 2 layers.

Maybe 3 elbows max

 

[binky]

machine mart used to do a good range of pumps

 

[poni]

use one like this, will last for years

http://www.mono-pumps.com/en-uk/merlin_industrial_pump?industryid=1869

 

[Apache]

Currently the lab is built (as of today) and there is the pipe buried in the slab.

Everything at this point is flexible - except the 20mm poly pipe is very much fixed.

 

[Marvo]

A newly built lab would be a lab puppy then??

A small jet pump maybe 500-750watts they're often used as a well point pump and they self prime up to about 8 meters and can run for limited periods with no significant head pressure. Look at the Pentax CAM series.

Is it potable water by the way? If it is forget the one I mentioned, you'll need a stainless pump.

 

[Apache]

Sometime in the next month, no great rush.

 

[Blue Duck]

if it's grey water then don't wash your car with it!

I know it's for washing sheep or something with 4 legs.

An organisation I have worked for in the past spent many thousands on rain water harvesting only to have it installed by muppets :animal:   it lasted less than a year.

not being able to access the pump didn't help.

 

[ProDave]

Most people that harvest rainwater bury the tanks. If you leave them out in the open, the water will go green and stagnamt. Since you haven't burried them, the best you can do is build a lean to shed around them to keep them in the dark.

Then a simple submirsible pump in the bottom of one of the tanks, that's definitely self priming.

 

[Andy™]

It can if its self priming with a water bowl (cant remember the name) type thing Gilkes do them and we fit a lot of them, they self prime some 20 meters ish

how can it self prime to 20 mtr? the most suction you can get would be -1 bar (or there abouts) which is 10mtr

 

[Tony S]

I used a combination of rainwater and bathwater as a source for grey water. Flushing the bog or watering the garden doesn’t need potable water. A small submersible along with level floats in the header kept the system supplied for what we needed. The water interceptor was buried under the garden.

A word of warning, the grey water system needs disinfecting every so often.

 

[Apache]

The water will be used for washing down the shed floor after treating animals. Sometimes it can be bloody etc.

Adding a jug of hypochloride every now and again is very doable. It's would also be possible to fill the header tank (the first time) with a hose so the transfer pipe would remain full of water. Unless I am mistaken there should be no need for self priming ability.

Whilst I have no problem with a submersible pump outside - I really wanted the pump controlled by a floatswitch in the header tank - as that is where I will be using the water. Having to manually fill the tank would be less satisfactory.

In an ideal world I'd have it so the pump was tripped when the header tank got down to half full and then refill to the top.

 

[Tony S]

The water will be used for washing down the shed floor after treating animals. Sometimes it can be bloody etc.

Adding a jug of hypochloride every now and again is very doable. It's would also be possible to fill the header tank (the first time) with a hose so the transfer pipe would remain full of water. Unless I am mistaken there should be no need for self priming ability.

Whilst I have no problem with a submersible pump outside - I really wanted the pump controlled by a floatswitch in the header tank - as that is where I will be using the water. Having to manually fill the tank would be less satisfactory.

In an ideal world I'd have it so the pump was tripped when the header tank got down to half full and then refill to the top.

No great problem with a small contactor and two float switches. Low starts, high stops.

Draw out the basics of what you want.

 

[Andy™]

The water will be used for washing down the shed floor after treating animals. Sometimes it can be bloody etc.

Adding a jug of hypochloride every now and again is very doable. It's would also be possible to fill the header tank (the first time) with a hose so the transfer pipe would remain full of water. Unless I am mistaken there should be no need for self priming ability.

Whilst I have no problem with a submersible pump outside - I really wanted the pump controlled by a floatswitch in the header tank - as that is where I will be using the water. Having to manually fill the tank would be less satisfactory.

In an ideal world I'd have it so the pump was tripped when the header tank got down to half full and then refill to the top.

if the pump is below the water level of outside tank then no need for self priming, it will constantly have water

if its at the header tank then a self priming would work, but they do seem to be slow at priming (at least my 3" pump is, it takes that long to prime i have a manual pump that connects to the output to suck the water through first)

best option would be a pump at the ground with a switch in the top tank