03-23-2013, 11:05 AM
It's odd to me that so many people mention bird poop on the roof when talking about catchment systems, when the bigger health risk seems to be from mongoose or rat urine, which can carry leptospirosis, a nasty bacterial disease which can have serious consequences, like liver failure. It's a fairly rare disease... only about 200 cases are reported in the US each year, BUT half of those are contracted in Hawai'i.
And what makes Lepto especially nasty is that you don't have to drink the water to catch it... you can get an infection in the shower, or washing dishes, through microscopic scrapes or breaks in the skin, and through mucous membranes.
So my friends who "go commando" with their catchment systems, depending on 5 mil swimming pool filters and an occasional cup of bleach in the tank to make their water "good enough" really scare me.
First of all, a 5 mil filter is merely a "dust" filter, taking out fine airborne grit and organic particles, but doing nothing about biological hazards like bacteria and protozoan cysts. And while chlorine treatment can be an effective prophylactic at high enough concentrations, the "punatics" I'm acquainted with tend to be too slapdash about how much and how often they add bleach to the tank to give me much assurance.
The UV units are good, but I don't believe they should be the first line of defense. Among other things their effectiveness drops as the bulbs age, and they need to be wiped down regularly. The Ozone Generators, ditto, but they are even more expensive to purchase, and with Hawai'i electric rates so high, they're both expensive to operate.
My holy grail has been to find a passive filter system that could operate without power, yet provide effective protection against the most common "biologicals." For the last two years I felt the best solution was the ceramic filter technology offered by companies like Just Water, Berkey, ProPur and others. Filter rating of .2 mil stops most bacteria and protozoas. Effective filter life 6 months, $25 - $60 rreplacement cost per cartridge. Downside: frequent filter cleaning required.
Recently I discovered the "hollow tube" filter technology pioneered by dialysis filters, as marketed by Sawyer, which has taken the camping and backpacking world by storm, as the filters are .1 mil , need cleaning (a simple backflush) only 1/20 as often as the ceramics, cost only twice as much, but have an infinite service life. And they have a PointZeroTwo Viral filter (that's .02 mil) that can be used for whole house filtering... which theoretically should be able to eliminate the UV unit or Ozone generator. To me that's a very intriguing prospect.
I'll dig into this some more and report back on what I find.
And what makes Lepto especially nasty is that you don't have to drink the water to catch it... you can get an infection in the shower, or washing dishes, through microscopic scrapes or breaks in the skin, and through mucous membranes.
So my friends who "go commando" with their catchment systems, depending on 5 mil swimming pool filters and an occasional cup of bleach in the tank to make their water "good enough" really scare me.
First of all, a 5 mil filter is merely a "dust" filter, taking out fine airborne grit and organic particles, but doing nothing about biological hazards like bacteria and protozoan cysts. And while chlorine treatment can be an effective prophylactic at high enough concentrations, the "punatics" I'm acquainted with tend to be too slapdash about how much and how often they add bleach to the tank to give me much assurance.
The UV units are good, but I don't believe they should be the first line of defense. Among other things their effectiveness drops as the bulbs age, and they need to be wiped down regularly. The Ozone Generators, ditto, but they are even more expensive to purchase, and with Hawai'i electric rates so high, they're both expensive to operate.
My holy grail has been to find a passive filter system that could operate without power, yet provide effective protection against the most common "biologicals." For the last two years I felt the best solution was the ceramic filter technology offered by companies like Just Water, Berkey, ProPur and others. Filter rating of .2 mil stops most bacteria and protozoas. Effective filter life 6 months, $25 - $60 rreplacement cost per cartridge. Downside: frequent filter cleaning required.
Recently I discovered the "hollow tube" filter technology pioneered by dialysis filters, as marketed by Sawyer, which has taken the camping and backpacking world by storm, as the filters are .1 mil , need cleaning (a simple backflush) only 1/20 as often as the ceramics, cost only twice as much, but have an infinite service life. And they have a PointZeroTwo Viral filter (that's .02 mil) that can be used for whole house filtering... which theoretically should be able to eliminate the UV unit or Ozone generator. To me that's a very intriguing prospect.
I'll dig into this some more and report back on what I find.