Grifaid is our charity, registered in England number 1135952, the objects of the charity are to relieve hardship, preserve health and support education in developing countries.

Grifaid is also the brand of our innovative water filters.

What is the Safe Water Trust?

The Safe Water Trust is a not-for-profit Company Limited by Guarantee, dedicated to developing and manufacturing water filtration systems for Grifaid and other Non Govermental Organisations.

What do Grifaid water filters do?

They remove biological contaminants and all particles (bacteria, viruses, cysts and protozoa) from water, making it safe to drink.

What is so special about the Grifaid water filters?

Due to the built-in self cleaning and back flushing design, our filters can last up to 6 years.
Easy to use and have a high flow rate.
There is no need for replacement parts.
No chemicals required for treatment.

Do Grifaid water filters meet international standards?

The most accepted standard is the US Environment Protection Agency guide and protocol for testing microbiological water purifiers. Grifaid Water Filters meet this standard for bacteria, viruses, cysts and protozoa.

How do Grifaid water filters work?

The heart of Grifaid Water Filters is a "membrane filter". The membrane filter comprises small tubes (1mm bore) with 0.00001 millimetre pores (holes) in their walls. Water flows up the tubes and the microscopic holes in the walls allow water to pass through. Dirt, bacteria, viruses, cysts and protozoa are held back. Sand and other coarse particles are stopped by the washable pre-filter, a gauze screen with 0.12 millimetre holes in it. Finer particles pass through the screen into the membrane, where they flow up and down the inside of the tubes, keeping them free from clogging. This dirty water is periodically flushed out of the system. Water is fed through the system with a hand pump.

Where are Grifaid Water Filters being used?

Grifaid Water Filters are in use in more than 50 countries, both in development and emergency response situations.

Are there contaminents that the filters do not remove?

They do not remove dissolved substances which sometimes occur in water from deep wells. Examples are salt, calcium, or arsenic. Where it is proposed to use a Grifaid Water Filter for contaminated deep well water, the water should first be analysed to find the nature of the contamination.

How do we know if the filters are not working properly?

The only way the filters can fail to clean the water is if there is a break in the wall of the membrane tube which will then allow dirty water through. Fortunately the membrane tubes allow water through their walls, but not air when they are damp (they are hydrophilic).This enables simple tests for air leaks which would indicate failure in the filtration. These test can be carried out by the user and are described in the operation manuals.

Can Grifaid water filters be damaged?

There are environmental and physical limits. They should not be stored under the direct exposure to the sun for a prolonged period of time. The membrane can be damaged at temperatures above 45°C. They should not be stored in places below 5°C. The membrane can also be damaged by severe shock.

How long do Grifaid water filters last?

The life of a membrane is subject to the quality of the source water. Minimun lifespan in expected to be 5 years, however we still have filters in use after 6 years with no loss of performance.

Do parts need replacing?

Our filters are designed so that replacement parts are not required. If our filters are not maintained as per the instructions, after extended use there is a possibility that the pump seal might need changing. We provide spare "O" rings with each of our filters.

Do chemicals need to be added to clean the water?

Our filters do not require any additional chemicals to purify the water. The membranes are particle filters.

With the Grifaid community filter can I pump directly from the well?

Using the community filter to pump directly from a well is not recommended, as it takes a lot of pumping effort to lift the water, considerably reducing the flow of clean water.

What are the advantages of a membrane filter over other methods?

Unlike chlorine tablets, our membrane filters completely remove all solid particles and organsims such as bacteria, viruses, cysts, and protozoa. Our filters are multi-use and are long lasting, without needing replacement parts. The filters are therefore able to provide a reliable, long term solution for producing safe and clean water with no chemical taste.

Can the filtered water be stored after filtration?

Water from Grifaid Water Filters is free of chemicals and clean water is available on demand. As a result, water should not be stored for more than a day as germs may get back into it through cross contamination. This is also the case with bottled water or clean well water.

What will the water look like after filtration?

The water will be clear and free from all particles. Grifaid® Water Filters do not remove substances which may affect the colour of the water.

What stops the filters from clogging up?

The filters have 3 stages of cleaning, the use of which depends on the condition of the input water:

Coarse particles are held back by the pre filter screen, which can be removed and washed off.
When pumping, water flows along the inside of the membrane tubes in both directions, continually washing them out. This is called cross-flow.
When back-flushing the filters, clean water can be pushed backwards through the pores, freeing any small particles stuck in them.

In rare cases, under extreme conditions, it is possible that biofilms may form inside the tubes causing the pores to block.