Rain water loft tank size

[AV1]

With little else to do .... I have set up a outside tank with what will be my take on this automatic de lux version pumped system of this
http://www.rainwaterharvesting.co.uk/proddetail.php?prod=RWH-SP-K03
to run my toilets but need make put a tank in my loft to suit, is there a minimum size that experienced people would use and reading through threads it looks like I might need a 12v timer set up to stop the pump chattering...any advice gratefully accepted.
Adrian

[fatbob]

Hi AV1,

I hate to see a post go unanswered, so here's my take on this (I'm by no means an expert btw).  I'm planning something similar myself in the future, the points I'm considering for the tank and control system are - space and access to install the tank, strength/structural factors of the rafters and capacity of the tank.  I'd look to install the biggest practical size I could fit through the loft hatch, perhaps around 100L+ to prevent frequent running of the pump.  For an 7L flush that would give you around 14 flushes per 'pump'.

There's some very good articles on control systems and circuit diagrams at http://www.reuk.co.uk/water.htm.  I even learnt a new word there - 'hysteresis' which is pump chattering to you and me.  There is an article called 'simple well pump controller' which is what I plan to base my control system around, with some kind of run dry protection for the pump should the lower storage tank run out.

Don't forget some provision for visible overflow on the header tank just in case things go awry with the control system.  Also to think about is how to switch back to mains for flushing the loos in the event of the rainwater tank running low.   Bear in mind the mains/rainwater separation needed for compliance with water regs if you want to fit a mains backup to the header tank.  Depending on your tanks and layout (and location !) you may need to think about preventing the system freezing up in winter also.

Food for thought I hope, I'll caveat all the above as my inexpert views  (there's many more wiser heads than mine out there) and best of luck with the system.

Cheers, Bob.

[AV1]

Thanks for that Neal at reuk cured my chatter with a bespoke relay..... and the rain is obviously keeping me happy.
Adrian@

[fatbob]

Glad to help  and yup enjoying the recent rain... free water is good !

[alecponting]

I recently bought a water tank from http://superwall.com.au/, its very nice and big in size which saves large amount of water.

[knighty]

have you had a poke in your loft yet to see where to put it ?

you really need it up against a brick wall, or if you're lucky and have an older house with brick internal walls you can put it above where 2 walls meet to form an X where it'll be nice and strong

100litres of water is 100kg.... which is quite a bit of weight up there if it's not in the right spot !

[JohnS]

I recently bought a water tank from http://superwall.com.au/, its very nice and big in size which saves large amount of water.

Where in Aus are you?

I hope it has not been filling up tooooooooooo quickly.