i had an idea pop in my head this morning.

This may be straying slightly off topic, but I'm also wondering when you say that this holds 'potable' water (i.e. fit for drinking), how you go about filtering bird feces out of the collected rainwater. I'm not sure how well a simple sand-filter might work, and I guess that awkward filtration step is why I mainly see rainwater cisterns, from roof&gutter collection, used to water gardens during dry periods, instead of for drinking.

I have looked into water tanks & systems to get or retain water.
The tank suggested in this topic is a good idea! But why not go with Ferrocement tank? Depending on capital resources, to build one of these would seem more cost effective.
Supplies are re-bar,wire to tie re-bar, cement, sand, water and corrugated sheet metal (like the kind used on roofs.) and plumbing pipe
Since OSE has CEB they can be used as well for foundation & tank cover. Ferrocement can also be used to build sinks, toilets and other items used in daily life. And these tanks can be built into the ground alone or add another tank on top of it for more storage. A sand filter could be used to clean gray waters that then feed into the storage tanks or used for irrigation , rain water collection on all points where run off can be diverted to storage as well. A second tank could be built and used for a small scale hydro electric gen or even smaller tanks can be used with solar heating for hot water.
There are several ways this could be approached and or looked at.  Check out EMAS's videos that have many great budget minded projects.

Hi guys and gals:

My thoughts on rain water tanks. The people at Good Earth Trust are already using CEB (interlocking in this case)  to build water tanks in Africa. They seem to be working quite well. I would think that you could use non-interlocking bricks relatively easily as well with the addition perhaps of some 3-4 mm fencing wire wrapped around each course to give it more tensile strength.

4ndy, bird poo? Many people in Australia (including myself from the age of 0 through to 12) live on "tank" water as their only drinking source. It's great stuff, doesn't come with any nasty chemicals (chlorine or flueride), things like "bird poo" aren't really a factor.

It's disappointing that the OSE guys didn't think outside the rectangle when designing the CEB press, it's inability to quickly and easily make interlocking and shaped bricks is why I'm designing my own.