Filtering Variability: Taking Control of Your Animal Drinking Water

Sometimes there's a million little reasons to do something, and when considering purifying drinking water for lab animals, a million may be true. Water can be teaming with bacteria, viruses and particulate that can sicken animals when ingested and forfeit the viability of research. While municipalities process water before it reaches the tap, the quality of processing can differ by location and time of year, which creates variability. Controlling purity by arresting contaminants through filtration is highly effective in producing healthy drinking water. This is determined by how effective filters in the system are at removing smaller and smaller contaminants. Particle capture size is a critical factor in choosing a filter, and in context a 1-micron (symbol µ) particle is equivalent to one millionth (0.000001) of a meter, or one twenty-five thousandth (0.00004) of an inch. A fine grain of sand measures approximately 250 microns in length. Below is an overview of some of the main filter types used to remove contaminants in vivarium drinking water applications.

What are Particle Filters?

Particle filters are responsible for removing larger suspended particles from the feedwater in an assigned grade. A 5-micron particle filter is a typical grade to start with when filtering feedwater. These replaceable cartridge filters fulfill a dual role of removing unwanted contaminants and preventing finer filters from occluding downstream. By example,
the Edstrom® Filter Bank Station uses three particle filters in series:  5-micron and
1-micron cartridges act as prefiltration to remove larger particles which will conserve the life of the third, finer 0.2-micron membrane filter cartridge.  


What are Sand Filters?

Sand filters are tasked with removing suspended solids and turbidity from an inlet source water. They can be used as a prefilter to extend the life of cartridge filters in cases of high feedwater turbidity. Sand filters can also be installed on the pretreatment line of a reverse osmosis system before a carbon filter to keep the carbon bed free of solids.


What Are Activated Carbon Filters?

Activated carbon filters are installed to remove chlorine, chloramines, and organics in water. For reverse osmosis systems using polyamide membranes, a carbon filter must be installed to remove chlorine that is detrimental
to the membrane. Carbon filtration is also highly effective against trihalomethanes, organics (such as chloroform) commonly found in chlorinated municipal water supplies.


What Is Reverse Osmosis?

The final filtration method employed prior to storage and distribution is the most effective - reverse osmosis. It produces the finest level of animal drinking water by removing impurities down to 0.001µ - the sub-molecular level. Reverse osmosis is a recommended choice when using specialized subjects such as immunocompromised, transgenic, and knock-out models. The process of reverse osmosis involves water being forced through a semi-permeable membrane by pressure. This causes the percentage of source water forced through the membrane to be purified as drinking water (the permeate), while the balance of the water and shed impurities (the concentrate) is sent to drain. The filtered permeate is then channeled to storage tanks awaiting distribution. A quality reverse osmosis system such as the Indigo RO should continuously monitor the water-making process and the permeate quality to ensure only the highest quality water is dispensed to the animals.

A Filtration Strategy

A tiered system of filtration technology is essential to removing impurities from animal drinking water. A water quality analysis can indicate the current state of facility source water and be the basis for developing a filtration strategy that brings purity levels to required specification. Avidity Science engineers can assist with tailoring a system of filtration suited to your needs. Click here to learn more.