Catchment tank filter question

[bgiles]

Agree with Terracore. You're doing all the right things, just add filters and UV. Less work than adding chlorine and mo bettah.

[MarkP]

Interesting thought here: There is some consideration given to whether hyper cleanliness can cause allergies. Getting certain childhood diseases is a necessary and desirable rite of passage. Are we forgetting that our ancestors drank out of mud puddles? Granted a lot of them died from it, but the idea that the water must be absolutely free of anything growing may be excessive as well as unrealistic.

Anyone familiar with slow sand filters? They are in some ways similar to a pool filter in that they are arranged so the water filters downward through a column of sand. However they are not "cleaned" the way such filters usually are, by back-flushing. They are designed to have a slow rate of water flow down through them. This of course physically captures many solids. However it is the biological activity in the first couple of inches of sand that does the real work. Far from creating a sterile environment, the goal is to create a microscopic wild kingdom where all the problematic stuff lives fast and dies young before it exits the filter at the bottom. In some respects it is a mini-leach field in a bath tub. You never back-flush the top layer in the classic sense but instead do something called wet harrowing, draining off the couple of inches of water that are normally maintained above the top of the sand as you stir up the top couple of inches of sand. The goal is to keep the organisms that live in the top layers of sand in the right place and not disrupt the layering too much, but still get rid of the solids that are obstructing flow.

Or buy a couple of $30 filters.

[VancouverIslander]

If you have a large tank it's probably a good idea to add chlorine once in a while to kill off it's resident population of bacteria and viri. It is short lived, but knocks down the resident population and is probably why the recommendation is to add chlorine monthly. U of H had a good guide on catchments. One interesting thing they say is that household bleach has not been approved for use so the safety conscious among us should probably consider an alternate source of chlorine (though perversely they don't say what source to consider)

In the end, though, filters are a very important part of the whole system.

[kalakoa]

The CTAHR Rainwater Management Guide:

http://www.ctahr.hawaii.edu/oc/freepubs/pdf/rm-12.pdf

[VancouverIslander]

That's definitely worth a read - it's what I used when planning my catchment.

[redefinehappy]

Hi everyone! I took a few days off in a "technology fast" during the holiday and returned to a lot of fantastic information here. It seems the consensus is to add a filter for the microscopic buggies and sediment and that should take care of any residual paranoia I have. We use the Nanawale taps for water, so as long as we can take care of anything that might get into small cuts or hang around on pots and pans, we it seems we should be safe.

bluesboy, I appreciate your information and recommendation of Waterworks. I am going to stop by there on my next trip into Hilo! Mahalo everyone!

kalakoa, I have a hard copy of the catchment guide you posted and it has been incredibly helpful. Thank you so much for posting the link to the online version, I've bookmarked it.

I may not have gone where I intended to go, but I think I have ended up where I intended to be.
~Douglas Adams