So...I'm about to do Rainwater Harvesting

[Nestor]

59 minutes ago, Stu789 said:

Does anyone have experience of direct feed rainwater harvesting systems (no attic tank) with automatic plant watering systems & also using a pressure vessel to reduce pump cycling?  

 

The hydroforce pump manual has a note:
"Pressure-sensitive pumps are unsuitable for use with low flow applications such as drip feed irrigation systems. To be used on such a system a pressure vessel must be installed and charged to 2.1 bar (30 psi)."

 

No experience with auto watering systems but have the Hydroforce pump on our rainwater system.

 

Had a problem with the pump working intermittently and speaking to the technical team they suggested I might have a leaky cistern and recommended fitting a pressure vessel to alleviate any issues.

 

Comments below from tech support.

"The pumps have a programme installed in them that is designed to stop the pump from burning out and also a leak detection device.

 

The pumps like a good constant flow rate of water to operate at there best, if the flow of water is restricted then the pump will believe that there is enough pressure in the pipework and stop pumping, only there might still be a small amount of water being discharged and thus the pump fires up again. So if the flow of water at the eventual outlet is restricted the pump will continually stop/start and eventually cut out". 

 

In the end I replaced the Pressure switch, Hall switch and the Non return valve and working fine now.

But would fit a pressure vessel for low flow.

 

 

Edited March 28 by Nestor

[Nickfromwales]

Pressure vessel, aka accumulator, is an essential bit of kit.

 

For RWH, anything less than 10,000L is a waste of time and money.

 

This is one sector where sales people are waaaaaaaaaaaaaaaaaaaaaaaaay better than the thing they're selling.

[Stu789]

Thanks - this is all useful.  Was thinking 000L but easy to go 7500L capturing from 200m2 of bungalow / attached garage roof.

The larger units don't cost much more than smaller sizes and extra digging/muckaway isn't large £.

Motivation isn't so much financial but rainwater management -> smaller attenuation pond, happy neighbours & severn trent.

[saveasteading]

9 hours ago, Nickfromwales said:

anything less than 10,000L is a waste of time and money.

Not sure I agree. I did put that size in once even though others said it was unnecessary. The principle was that with 500m2 of roof it would store every raindrop in summer storm, when it is otherwise scarce. And it fed 6 x wc. 

In most situations it will only be for gardening and whatever m3 can be fitted in is a boon. I'm using free redundant oil tanks off Marketplace. So they will come as 2 or 3m3 typically. Any oil plumber will also be happy to get shot of them.

Unless you're a market gardener of course when you need more and don't want any oil traces.

We are designing the garden for minimum water demand.  Meadow, prairie, dry garden areas and no lawn as such.

[Nestor]

3 hours ago, Stu789 said:

Thanks - this is all useful.  Was thinking 000L but easy to go 7500L capturing from 200m2 of bungalow / attached garage roof.

The larger units don't cost much more than smaller sizes and extra digging/muckaway isn't large £.

Motivation isn't so much financial but rainwater management -> smaller attenuation pond, happy neighbours & severn trent.

Just some advice regarding the overflow due to excess rainfall and saturated ground.

 

We had water coming out the top of the chamber lid a few times even with plenty of soakaway crates.

 

In the end I dug down and cut a large hole in the soil pipe for excess to fill the crates and then added a 110 triple socket to extend the run to exit above ground for the excess.

 

 

[saveasteading]

1 hour ago, Nestor said:

water coming out the top of the chamber lid

If it wasn't escaping there then it would be coming out of manholes upstream, or from downpipes.

You should not send it to the soil pipe, as that is what causes overflows at the sewage works.

Have you space for a ditch or pnd?

[Nestor]

1 hour ago, saveasteading said:

If it wasn't escaping there then it would be coming out of manholes upstream, or from downpipes.

You should not send it to the soil pipe, as that is what causes overflows at the sewage works.

Have you space for a ditch or pnd?

Private sewerage here.

Tank is below the house, have about 330 sqm of roof so can fill very quickly.

The rainwater tank is completely separate to the treatment plant.

Soil pipe general term for 110mm.

 

 

[saveasteading]

19 minutes ago, Nestor said:

Soil pipe general term for 110mm.

Where does it go? Best find another term if presenting this to anyone, Soil specifically means sewage and black water, but I appreciate that merchants use it as a general term for drain pipes.

 

19 minutes ago, Nestor said:

330 sqm of roof

That is indeed a lot of water. It used to fall on the land. Do you know if it drained away or caused any issues?

 

I like to use long french drains if the land allows.  ie not clustered together but heading different directions to spread the waterr, but also with more chances to find porous areas or old root voids.

[mads]

On 28/03/2026 at 08:44, marmic said:

no idea about plant watering but we have sucessfully installed 15000litre underground potable tank with pump controlled by pressure switch/pressure tank.  filters before tank. Once in house water goes through 3 stage filter then UV - feeds into hot water tank (set at 55° - which as far as i know will kill anything) /hot taps/shower and cold taps/washing machine/dishwasher/toilet cistern. Water not completely clear with tanins still present but not bad at all. Think this will improve however over time as found about 6 weeks ago groundworker was incapable of following clear instructions regarding tank overflow - I've done a temporary fix - another job on list for summer!  

 

Could you share more on your approach to filtering before and within the house please? I'm particularly interested in the UV and also how you are thinking to reduce tanins.

[Nickfromwales]

4 hours ago, mads said:

 

Could you share more on your approach to filtering before and within the house please? I'm particularly interested in the UV and also how you are thinking to reduce tanins.

What capacity tank are you thinking of using? At 5000L or under I'd really not bother.

[SteamyTea]

Our old member @Jeremy Harris used an ozone generator, instead of a UV lamp, to kill the nasties. Worked well.

Having said that, it was before cheap UV LEDs were available.

I like the ozone method as it, by it's very nature, gets well mixed in with the water stream, and works better at elevated pressures.