Rain Water Harvesting - where do I start?

[lfnfan]

Hello

I recently moved into a place with my own garden and a water meter

so my thoughts are turning to capturing, storing, and using rainwater via the guttering. Might be open to grey water ideas, but I think this route is expensive.

I would appreciate any ideas re things I should consider when choosing a rain water 'system'.

Questions going around my head are:

- general question: how long is stored water 'good' for? Does it go stagnant after a while and nasty for plants? Does it need 'treating'? Can I use winter's water all the way to autumn?

- general question: will I be able to run stored water through an irrigation system without it getting clogged up?

- general question: any dangers to 'burying' the butt under the garden / patio?

- general question: do certain butt materials last longer than others? What is general expectation for service life?

- general question: are there any good stockists I could look at to get an idea of products / costs?

- me-specific question: how big should my butt be?

- me-specific question: how strong should my pump be to drive water round the irrigation system

any advice much appreciated.

[dave_norm_smith]

Hi

I really need to get some of these set up this year as well. I think your first thing is where is it going and how precious your view of them is?

A lot of the forum users use the blue food barrels and link them. ie. down pipe goes into first and when it gets near to the top a pipe is located and connects to the next in the chain for the overflow. You can daisy chain as many of these together as space allows.

However as with my own, my veg are in the front so a big ugly blue butt in the front garden is not going to look good, so I will have to bite the bullet and get a nice one for there.

I dont think I would bury them as its going to be a heck of a job if you need to replace, empty etc.

If the butt has a tap, dont forget to raise the butt high enough to take a watering can.

I dont think during the summer the water will be in there too long to go stagnant, maybe just a bit green. The green will probably block your irrigation system though.

And if you need a pump, you'll need a dirty water pump, something like this

Buy Challenge Xtreme Dirty Water Pump 400 Watt at Argos.co.uk - Your Online Shop for Compressors and pumps.

Anything else will be bunged up within seconds.

Hope some of that helps

Dave

[lfnfan]

Hi Dave

view is a key consideration - we are not so keen to have it on display, which is why I would like to find out about the possible down-sides of burying it under the garden. The most likely above-ground site has already been earmarked in my mind for a greenhouse

We will have the builders in at some point, so digging a large hole is not something that puts me off burying a butt.

thanks for the heads-up on the pump!

[dave_norm_smith]

Rain Savers

This may help for some options and the perfect solution for you is near the bottom but I worry when they dont offer a guide price! lol

Is there no room to slip one at the side of the greenhouse and cover with screening?

Dave

[lfnfan]

how funny - I came across the same website, and dropped them an email re price. will let you know what they come back with.

the other product I came across was here: www.freerain.co.uk

I'm definitely not ruling out above-ground, but am interested in trying to figure out all the main options and their limitations.

[Two_Sheds]

I'm no help to you, my irrigation system is this

[Potstubsdustbins]

Depending on the type of water storage vessel you choose i.e. shape size etc the problems with underground storage will vary.

General problems will be access to retrieve the water and for maintenance and over flow. If you just want to store the water for later use then the first two problems are easily solved.

You could use a length of 110mm soil pipe fitted with a access cap running down into the vessel. All plumbers merchants less than £20. You would then use a dirty water irrigation pump, this type of pump is portable and can lift the water out of the storage vessel without actually being lowered into the vessel itself. 900watts, 60 l.p.m, max suction height 8 mtrs, max delivery height 42 mtrs. £53-54p plus postage Screwfix.com.

Simple remove access cap drop in suction hose switch on and hey presto.

The simply way to handle the over flow water would be to dig a trench at the required depth and run a length of plastic pipe away from the vessel. This pipe should be drill at intervals along its length to allow any excess water to run of under ground and not cause localised flooding. Get the height right and you may just invent the first underground irrigation system.

As to the storage vessel itself the first thing is to try and work out how much water you would like to store and how much space you have and how deep are your pockets.

If you are thinking of just digging a hole dropping in a plastic vessel and then back filling around the vessel then most square tanks would prove unsuitable as they would not be strong enough when empty to prevent collapse. Good quality round tanks would be the prefered option and you could link several together using standard plumbing fittings. These tanks should be back filled using washed sand all builders merchants.

This method would also remove the need for a chamber cover to stop people falling in the hole.

Things to think about. Are there any underground services in the area drains, gas pipes electric cables etc. The weight of the water 10lb per gallon 6.25 gallons to the cubic foot.

Good point water stored underground is not affect by sunlight so no plant growth.

It is do-able but would need some thought and planing.

Colin.

[lfnfan]

@ Two_Sheds

definitely ticks the 'keep it simple' box.

good colour too.

[Kristen]

Each time I look at rainwater harvesting the cost puts me off. I think it needs a tank of 5,000 litre (i.e. 5 cu.m) tank to cover for drought periods, and they cost plenty (thousands rather than hundreds). Metered water is about £1 per cu. m.

Might be worth you reading your meter each week to get a feel for how much you use now, and again in the Summer when you are watering the garden etc - and the difference would be your "garden" use.

If you installed a grey water system to fill loo cisterns with rain water then there is an additional saving (more cost too though ) - but from what I have read you would be hard pressed to save 25% of your in-house water - although you might save 100% of your garden water if your tank is large enough for drought periods.

We use twice as much water in Summer as Winter. The amount that we could save is a few hundred pounds a year (by my calculation). We are not on mains drains, so we have no benefit from a reduction of that (for those on mains sewerage you are charged according to how much metered water you use, so if you use less water you pay less for sewerage too).

When our septic tank gives up the ghost I will replace it with something that will convert the dirty water into something good enough for irrigation, but until then its not cost effective for me.

[Two_Sheds]

definitely ticks the 'keep it simple' box.

Oh, and I use one of these in the summer to pump out the bath water onto the borders and lawn

[lfnfan]

@Two_Sheds - clever. And I thought it was going to be a bucket!

@ Kristen - you are about three steps ahead of me! I will definitely do a cost comparison once I've sussed my approach to rainwater harvesting and planned and costed out all the hardware. In terms of capital outlay, I would be happy with a break-even horizon of 3 years. So based on your savings, about £600. Our garden is approx 50ft by 20 ft, with 1 metre borders on 3 sides. Will also be some pots on the patio. And maybe a small veg patch in the future (!). My usage calcs will be very back-of-an-envelope. Complicated by the fact that at the moment, I can't read the dial of my water meter as it's totally fogged (thanks Veolia). Your 5cu.m estimate is interesting - how did you figure it out?

@ Potstubsdustbins - thanks for your post - lots of good practical info, and I like the sound of your proposed solution. Particularly that there won't be a chamber cover for inquisitive kids to be tempted by, and that it can be done using 'standard' kit. Can you point me towards a suitable vessel manufacturer - this seems to be the one bit of specialised kit?

many thanks!

[Kristen]

@ Kristen ...Your 5cu.m estimate is interesting - how did you figure it out?

A combination of things. I looked at our water usage (comparing Winter and Summer meter readings), and how long we typically have droughts for, plus allowing some Winter-to-Summer storage.

You can stick a formula into Google (in the place of a Search) like

10 metres * 20 metres * 1 inch =

for the amount of water you get from an inch of rain falling on a 10 x 20 M roof. By default it will give you Cu.M, but you can have Litres or Gallons:

10 metres * 20 metres * 1 inch in litres =

10 metres * 20 metres * 1 inch in imperial gallons =

I also looked at historical records from amateur weather stations near me using

Welcome to Weather Underground : Weather Underground

East Anglia is one of the driest parts of the country, but in general most of the UK gets 2" per month every month (on average), but I looked at how long the droughts were, and calculated how quickly the tank would replenish after Summer rain (or not!) which in turn led me to how much Winter rain I wanted to store until the Summer.

There are economies of scale - the plumbing from downpipes to tank, the need for a filter, pump, and to a certain extent cost of delivery to the property and installation, are fairly constant, thus putting in a tank twice the size is a long way short of twice the capital cost.

But, having said that, we have a larger garden than many ...

[taff]

you could always go with the linked water butts thing but screen them

[Potstubsdustbins]

With regards to the water storage vessels I have a couple of ideas.

First cheap and cheerful Standard water butts 1240mm high x 360mm dia 100 lts or 22 gallon £24-98. 920mm high x 530mm dia 210ltrs or 46 gallon £29-98. This type of butt is specially shaped to prevent distortion under weight and so should be OK when empty. They are also equipped with a tap which when removed leaves a standard 1/2" or 3/4 Bsp female thread at the bottom of the butt making linking together very easy.

Good point cheap. Down side may have to consider some form of overhead protection as the lids take no strain and are weak.

Another suggestion for you to look at would be plastic oil storage tanks these come in all shapes and sizes your local plumbers merchant would advise.

Good points totally enclosed, lots of standard tappings to make connections. Down side expensive.

Colin

[Potstubsdustbins]

As an aside to the actual post this project brings into mind of something similar that I did some years ago, well it was water.

A good friend of mine decided he would like to breed tropical fish. Not the standard shop bought tanks for this guy he made his own lots and lots of them.

He then decided to look at filtration the cost to complete the system with equipment bought from the 'fish trade' was enormous so he asked for advice.

My first move was to visit a aquarium supplier, what I found was basic plumbing fittings and pipe work at a vastly inflated cost.

We eventually used 4x45 gallon plastic water tanks as found in your roof space filled with various filter media. Standard fittings and pipe work and a bronze potable water pump all bought from my plumbing supplier. Job done for about 25% of original costings.

The point I trying to make is that as water storage is quite a new business and seems to be 'specialised' may not the same thing be happening.

Colin.