My husband has been in the water treatment business for over 25 years. He specifically helped us select the type of filter to match the current conditions in Puerto Rico: absence of running water (i.e. water that is under pressure and thus can be pushed through a filter housing), poor quality raw water sources, the lack of electricity and scarcity of fuel and lack of availability of transportation for recipients to travel to a central distribution point. Also, the availability of air-based shipping resources is limited. So, the filters had to be light and compact.
Given those conditions, we are currently using rugged two-stage gravity filter elements of a type that has been in continuous use in this type of environment since the 1830s. The first stage is a ceramic shell that provides an effective barrier against sediment, silt, and microorganisms. The core (the second stage) is a carbon block filter capable of reducing organic chemical like pesticides as well as basic taste and odor causing substances. The filter elements are installed in the bottom of a container like a pail which becomes the receptacle for the raw water. The outlet of the filter drips the product water through the bottom of the first container into a second receptacle – a second pail, cup, pot or whatever else is available. Each filter being assembled on the ground in Puerto Rico.
The filters produce water very slowly and are designed to supply drinking water to a household and/or an extended family or group of neighbors. Operating these filters does not require any expertise or specialized skills. The ceramic portion can be cleaned by hand as needed. This type of filtration can be maintained to last for years. We have chosen to go with an upgraded version involving the second stage of carbon filtration to reduce organic chemicals. The carbon component has a limited capacity. It will lose its effectiveness after a finite number of gallons treated depending on the load in the source water.
As the situation changes/improves in Puerto Rico, we are likely to review the technology we are using and make changes if warranted. For now, our choice of technologies it perfect for the current conditions.