Sun then rain offers silver lining

Mon, Apr 27, 2009

rainwater harvesting


Yesterday, I visited a glorious garden near Lewes in East Sussex where the blossom on the trees looked simply stunning in the sunshine – it was truly magical as you can see from my photo above.This was the culmination of 10 days of truly spectacular weather with temperatures reaching 19c and literally no rain.

Today, I awoke to  more typical April showers  – the blossom will really suffer in the rain. So will the more tender plants that  some gardeners may have been tempted to plant outside when it was warm and sunny last week. They are in for a bit of a shock – its down to 10c  and 5c forecast for tonight.

The delights of english gardening!


Time  to think about how rainwater harvesting is increasingly important for our gardens  as we experience less regular rainfall patterns like this.

Read these interesting articles by the UK Rainwater Harvesting Association which explains more about this subject

Check out Freerain who specialise in designing, supplying and fitting a range of rainwater harvesting systems

Marcus Fox from Freerain is a rainwater harvesting guru who has provided this introduction to inspire you to seriously consider the value of a domestic or business rainwater harvesting system. The initial costs may seem high but, the pay-back will last forever  – extreme winter rainfall is here to stay!

Marcus writes his own blog which has excellent practical and technical advice:

Or ‘wet’ your appetite with:

Rainwater harvesting is not a new practice, but since the introduction of
clean and reliable water supply during the Victorian period the practice of
collection your own water fell out of practice.
In Germany rainwater harvesting is much more common and they as a country
have been leading since the 1970s. In the UK a few companies including
Freerain Ltd have been supplying a range of systems and together these
companies formed the UK rainwater harvesting association. One of the
associations aims is introduce standards in to the industry. A new British
Standard is due to be released in the next few months which should help to
reduce the number of poorly designed and in some cases illegal systems.
A well designed rainwater harvesting system should always include a filter,
either on the downpipe(s) or an underground inline filter. This prevents
too much organic matter entering the storage tanks and protects the pump
and/or blocking of hoses and spray heads. For storage volumes larger than
about 1000 litres, the system really should be underground, this is in part
due to the aesthetics of having a large tank above ground around the house.
Importantly, an underground storage tank is more expensive to install but
they have several advantages. 1) It’s much easier to get the water in the
tank and through filters using gravity. 2) The water is kept dark and cold,
reducing the rate of algal growth and bacteria.
Other aspects of a system should include a calming inlet which allows the
water to enter storage smoothly and helps to retain oxygen levels and
promote good (aerobic) bacteria.
It is important that a system is sized to overflow a few times a year, this
helps to remove a scum layer from the tank and helps circulate the water. A
tank which is too large is not good, for two reasons. 1) The customer will
be buying capacity they will never fill and secondly, the water quality will
be much lower as the it will be turned around quickly enough.
A domestic system can supply around 50% of the demand for an average house
and substantially more for other applications such as gardens. This of
course depends on the available collection area (roof), the local rainfall
and the efficiency of the collection system.
We are often asked about how we calculate the system of tank, especially by
gardeners. They are sometimes concerned that we are advising small tanks
compared to their proposed usage. But it actually rains significantly about
every 18 days in the UK and even during hot periods, an hours thunder storm
can replenish the tanks very quickly. It’s important to give adequate
coverage, but it is not worth chasing every single last drop.
Costings (underground)
A domestic system (for WC flushing, washing machines & outside tap use, with
mains back-up) you will need to spend around £2000-2700 + VAT supplied
A garden system for garden use only, from about £1400 + VAT, supplied.
Installation costs vary and really a domestic system should be considered by
new-build projects or complete refurbishments. This is because it is
necessary to amend both drainage and internal plumbing and if this is in an
existing house, then this will prove costly. For a planned new-build, I
would budget around £800 for the installation.

This post was written by:

- who has written 872 posts on My Climate Change Garden.

I am not an experienced gardener - more of an enthusiastic amateur who learns by trial and error and who is keen to "manage" the effects of shifting weather patterns on my garden. Writing this blog is my passion and it has evolved over 12 years to inspire engagement with climate change outside our back doors, in our personal gardens and green spaces. My mission is to fertilise and expand this platform to grow a community of global gardeners communicating about the effects of climate change on our plants and exploring how each individual can make small changes in our lives to become more sustainable. The future of our gardens and #OurPlanet is in our hands - please plant your own seeds for our collective sustainable future.

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1 Comments For This Post

  1. Jo Moulds Says:

    I came across your lovely blog via Google Alerts and wanted to let others reading in the UK know about another rainwater harvesting business that mainly caters for the south-west and Welsh market – Rainharvesting Systems Ltd based in Gloucestershire.
    Rainharvesting Systems supplies systems for the residential market – new build and existing buildings – in much the same way as Marcus and Freerain and his excellent explanation above.
    My job for Rainharvesting Systems is to promote rainwater harvesting in general so I hope you don’t mind me adding to this blog. There are more systems out there than I think people realise – for example, Rainharvesting Systems has recently completed the rainwater harvesting system for underneath the new King’s Cross St Pancras International Terminal, various new-build schools and two new leisure centres in Watford.
    As I start to work with them more (my background is marketing, PR and journalism), I’m hoping that everyone installing systems puts information/interpretation notices about this up in public entranceways. This will be a great help in letting people understand that the systems can be put in place – both in large newbuild schemes and also for houses and gardens.
    Good luck with everything and I will keep an eye on the blog.
    Kind regards,
    Jo Moulds