Better rainwater pre-tank filter?

[al_uk]

Looking for ideas to improve the filtering of the rainwater before it gets into the IBCs. Currently using a 100 micron mesh water bucket filter in a standard bucket with a hole in the bottom, which is sat on top of the IBC filling hole. I then have a 5 micron filter bag which fits in the IBC filling hole itself. The gutter diverters are Technik 3P.

The mesh filter gets clogged almost immediately during rain, and neither it nor the filter bag can cope with the flow in even moderate rainfall. The roof is approx 100m2 and most of that ends up going through this filter.

I could get a larger 200 or 400 micron filter, but then the silt will just clog the filter bag, or end up in the tank.

There do seem to be some rainwater pre-tank filters available but they are quite expensive. Does anyone have any experience with them?

[Justme]

Can you not add more stages to your existing system?

Start with a small metal mesh / grid to catch the leave & work down to the 5 micron filter in 3 to 5 stages.

[al_uk]

Could do...

I could get 3 of these stacking boxes and put 3 grades of pond filter media in them.

http://www.amazon.co.uk/dp/B0012336PU/ref=asc_df_B0012336PU4449313?smid=A2DICHIH6QJA6P&tag=googlecouk06-21&linkCode=asn&creative=22218&creativeASIN=B0012336PU

Actually, maybe I should just get a gravity pond filter... I'll have a look

thanks!

[Justme]

Sorting out filters is near the top of my to do list at the min anyway.

We have a borehole that fills a storage tank & then gravity feeds our booster pump/pressure vessel. After the pump we have a disposable 5 micron pre filter & then a Rio2000 sterasyl filter. It all works great apart from the Rio needing cleaning out about every 3 to 4 weeks as the flow slows down. I am going to drop the pre filter down to 1 micron to see how that goes as they are only about £2 each & the 6 sterasyl's are nearer £45 for a set. OK you can clean them but each cleaning removes some of the ceramics so they will be cleaned away in the end. The existing 5 micron is stopping some stuff but is still allowing full flow after 2 or 3 clean cycles of the Rio.

Might need to add a second pre filter so it goes 5 micron - 1 micron - Rio2000. But we will see.

The main issue is we are such low users that the bore hole is not kept flushed clean enough. The storage tank take off point is about 1/3rd of the way up so we dont suck in any sediment & the bottom take off is used to water the garden so sediment cant build up. I think also that putting a baffle on the filler point so it does not stir up the contents might help too as a 2000+L per hour is quite some flow from the bore hole pump.

[Mike N.]

We have 'hedgehog' in the gutter to keep leaves etc out, then three increasingly finer grades of plastic pond filter stuff (holes are definitely not measured in microns!)before it goes into the IBC, then I pump it through a 'sock' - a sort of fabric bag. Then we add a bit of Tesco's value bleach and swim in it.

Mike

[al_uk]

I put a hedgehog in the gutter this year(!), on a gutter that gets completely blocked with leaves. The gutter has not yet blocked this year. However, I think the reason my filters are blocking quickly, is that the smaller leaves are breaking down (as they are supposed to) and the smaller particles are ending up in my filter rather than being washed down the sewer as small leaves.

Do you have a photo of your gutter to IBC filter setup?

If you use straight bleach in your pool rather than pucks, then I managed to find a much cheaper source of chlorine than Tesco value bleach if you're interested.

[Justme]

For the leaves problem you can set up a self cleaning screen that washes its self of any collected debris.

[dhaslam]

I have used three pond foam filter sheets,  1 metre by  .5 metres, slightly trimmed to fit in a   small tank.     Rain water is quite clean  so it really only uses  the top coarse filter.   It is also used to filter the pond water  and that mainly  affects the bottom sheet which is the finest.     The layers are suspended on netting wire on a frame.    So far  it isn't cleaning the water as well as I expected  but  because of  the large water volume it may stay fairly  clear after the initial filtering.   

[odbob]

A bit late in the day, for those who have already installed, but my rain water system consists of welded UPVC pipe from the gutters to the storage tank and so using the head of water as it rains, all the water is forced upwards through a vessel containing filter sand and gravel just prior to the tank, needs cleaning just once per year

[derekmt]

new here...
Filtering the rainwater has been a bit of a problem for me. At present I just use water butts with siphon outlets (to scoop below the surface at the top) as a pre settling for the covered over swimming pool tank. (effective capacity about 30 tonnes)
The issue is with   160sqm  of collecting area is having a filter that can cope with summer storm flow? any ideas?

[al_uk]

Right then! I'm going to have another go at this... I've been using coarse, medium, and fine pond filter media in a bucket like dhaslam, but still not particularly happy with it.

I'm now considering making a gravity based 'fast' sand filter like the "Greywater Filter" on this page http://www.reuk.co.uk/Sand-Filters-for-Greywater.htm

I have either a 4 gallon open plastic header tank, or a 20 gallon open plastic cold water storage tank to use.

I'm thinking of filling one of the tanks with about 100mm of gravel then the remainder of the tank with sand. The gutter down pipe would be diverted into the top of the tank and then an outlet at the bottom of the tank would lead into my IBCs.

Questions that come to mind

1. What sort of sand should I use - silica pool filter sand?
2. Will any old gravel from a diy shop do?
3. Will the gravity flow rate be sufficient through the 4 gallon tank, or even the 20 gallon tank?

Assuming max rain rate is 20mm per hour, and 100m2 roof, then max rate required is 33 litres per minute.

Any opinions welcome!

[RobNute]

A quick search found this,

http://www.productspec.net/products/16725/tanks-alot-ltd/first-flush-and-rainwater-filter.aspx

Not sure how effective it would be but looks like agood idea, I would have a search around Australian and New Zealand sites as its completely normal outr here to live of tank water and all the normal issues exist , leave etc, so they have probably come up with a solution for most things.

Best wishes

Rob

[RobNute]

More here.

http://www.marley.co.nz/afawcs0119271/CATID=1/SUBID=70/Rainwater/Rain-Harvesting.html

[al_uk]

Hi Rob, thanks for the links. I already have one of these http://www.rainwaterharvesting.co.uk/filter-clean-rain-ultra.php which is a 1st flush diverter and leaf catcher. The leaf catcher seems to work well but quite a lot of water seems to go down the drain for some reason. I actually have the 3p diverter underneath this unit so that when I need maximum yield I can have them both diverting.

I am still getting a reasonable amount of sediment in the tank, hence the interest in trying a sand filter. The sediment is from roof tiles which are wearing out.

[winny]

We collect rainwater for all our water needs as we're not on grid.  All our roof water is fed into a filter barrel (20 litres) which has a baffle between the inlet and outlet and the barrel is filled with ceramic pond filter media, sort of cotton reel sized hollow ceramic tubes that are very porous.  These trap alot of the debris off the roof such as lichens, wind blown grass etc.  The baffle forces the water down through the media and up to the outlet.  This goes through to another settlement tank (20 litres) that is there to collect any extra bits (none in the 2 years it's been operational!) Then the water is fed into the underground storage tank.

I check the filter tub about every 6 months, remove the media, wash it and drain / flush the filter barrel.  Work well and seems to cope with all the rain Scotland can throw at it but it does have an overflow just in case.

Hope this helps, winny