What are the limitations of your products?
- The ceramic shells are fragile and will break if dropped.
- The chemical treatment (activated charcoal) only lasts for a limited amount of water. (3000 gallons or so) A side note here is that many vendors claim a lot longer water treatment capacity but they do NOT treat for chemicals.
- The filters do not work on salt water
What are the physical dimensions of these filters?
The filters are domed shaped with dimensions given in the format (diameter of base x height of dome) in inches. For example a 4x4 filter will measure 4 inches in diameter and 4 inches tall from the bottom plate to the top of the ceramic shell. A threaded spout 1.25 inches long and 0.5 inches in diameter protrudes from the center of the bottom of the plate. Each filter comes with 2 silicone washers and a threaded nut.
How much water can be treated?
The ceramic filters will remove bacteria from water indefinitely (as long as the ceramic shell is intact). The activated charcoal inside a 4x4 filter will last for 3000 to 4000 gallons. (About 6 to 8 months of regular use in a gravity drip system.) The small 2x3 filters can treat approximately 60 gallons.
Do I need to provide additional treatment to the water?
These filters have been used around the world 'as is' with no additional treatment made to the water. However we get repeated requests about using chlorine as an added precaution. You can pre-treat or post treat the water with a small amount of chlorine bleach, If the water is pre-treated the activated carbon will remove the chlorine during the filtering process but this will use up the activated carbon faster. Post treating the water will extend the life of the filter's chemical removal.
If you are using bleach; stir it into the water well, and allow it to sit for 30 minutes for maximum effectiveness.
How much water can I get from a filter in a day?
A 4x4 filter in a gravity fed drip system, using a 5 gallon bucket with a single dome filter can filter 12 to 15 gallons of water per day. (The shape of the container can affect the flow slightly, deep containers that have a lot of water above the filter work faster and shallow containers work slower.) Using a simple siphon hose can increase this by 2 to 3 times (when used in a bucket). If more water is needed extending the siphon hose length or pressurizing a system can yield a lot more (depending on length of siphon or amount of pressurization). Please note however that a single filter used in a gravity drip system is deemed to be 'family sized' and capable of providing enough clean water for drinking and food preparation for a household for 6 to 8 months, with occasional cleaning (see maintenance section below).
In silty water (silt is very small suspended solids in the range of the filter pore size) the flow rate will drop off rather quickly as the pores clog up. Using pre-filter socks or other pre-filter barriers can help in these situations. Fortunately this situation is not common.
For folks interested in building group sized systems, here is a table of possible flow rates versus system type and number of filters used (note that these are optimal rates without refill times and low water turbidity). Higher flow rates are possible with larger containers and more filters..... (Please note that we only include instructions for single filter systems with our shipments.)
How do these filters work?
The basic filter consists of two separate elements.
First the outer ceramic shell filters out bacteria
. It does this because the pores in the ceramic that let the water pass through are too small for any bacteria to get through. The filter pores are around 0.2 microns and bacteria range from 0.5 microns to 10 microns.
for basic info on bacteria.) The lab reports below show that for particularly dangerous bacteria these filters are practically 100% effective.
The second element is the activated charcoal which is inside. This filters out many chemicals through a process called adsorption. (See more about activated charcoal below).
A third filter element, the pre-filter sock, can be added and is mainly for applications where the water has a lot of larger particulates in it such as ponds and streams. In comparison to this double or triple filtering, most store bought water filtration systems just use activated charcoal and are designed specifically for use with tap water as the source.
Do these filters have silver in them?
Can you replace the charcoal in the filters?
No, the filters are sealed cartridges.
How effective are these filters?
All of our filters are rated at 0.5 microns absolute (0.2 microns, nominal 98%) See the following for an explanation of the difference between nominal and absolute ratings:
E. Coli Test
Do these filters remove minerals?
No the size of the mineral particles dissolved in water are usually much smaller than 0.2 microns so they are not removed.
Where have these filters been used?
These filters have been used in disaster relief situations around the world for many years as a simple and cheap technology that has enabled clean safe water in the absence of any infrastructure. Check out http://www.texasbaptistmen.org/Ministries/WaterPurificationMinistry/tabid/480/Default.aspx
for pictures, testamonials, and to see exactly what these filters are capable of. You may also donate to the cause of clean water ministry at that website.
How can the flow rate be increased?
One of the few complaints received about these filters is that the flow rates are slow (due to the small pore size of the ceramic). This can be rectified using one of three methods or any combination of them. First you can simply add additional filter elements to the system; for example if one filter element in the bottom of the bucket is giving you 1 gallon per hour, adding a second element next to it will double your flow rate to 2 gallons per hour. (A standard 5 gallon bucket can fit 3 filters in the bottom.)
Second, adding siphon hoses can increase the flow rate of non-pressurized bucket systems two to three times and still just use gravity. Extending the siphon height further can greatly increase the flow rates but this means you need taller buckets or you have to separate the buckets and just have the siphon connecting them.
Finally, you can increase the water pressure to force the water to go through the filter faster. This is the idea behind the pressurization kits and lids you see for sale in the products area. Pressurization requires either manual pumping or an some kind of powered air pump. (The maximum recommended operating pressure for the filters is 45 psi).
Note that most people do not need higher flow rates; the basic drip systems have provided adequate amounts of water for hundreds of thousands of folks all around the world.
Which shape is better: the dome filter or the candle filter?
We have a small study here that looks at the surface area and the enclosed volume of the 4x4 dome filter and the 2x10 candle filter. In our opinion the dome filter has an advantage. Here are the details: Filter Shape Study
Siphon Details and Tips:
The size of the siphon tubing used for the standard 4x4 filters is 5/16th OD x 3/16th ID. We use food grade clear vinyl tubing as it has good flexibility to roll up for storage and shipment and straighten for use. If your tubing is bent and does not straighten out you can heat it gently (we suggest a hair blow dryer). After it has been warmed up you should be able to straighten it by pulling on both ends.
The siphon press fits directly into the spout opening of the filter. Sometimes it can be tricky to fit it into the opening. A good tip here is to cut the end of the tubing at a 45 degree angle.
Note: The siphons are an optional item and the filters will work fine without them (the flow rate will just be slower).
Is there a trade off between flow rates and filter effectiveness?
There is a trade off between how fast the water flows through the charcoal and how much the charcoal adsorbs. Because adsorption rates for different chemicals vary there is no easy answer on the impact. It is best to filter water at the rates that you need. (Many of our competitors do not filter for chemicals at all).
Where are these filters manufactured?
A common question we get is about the source of our products. Some products (the filters, socks, and pressure pumps) are manufactured in China, other components (siphon hose, buckets, pressure seals) are manufactured in the United States.
What types of plastic containers are safe to use?
Note that the buckets we ship have pretty tight fitting lids that can be difficult to take off if they are snapped on. They work fine with the lids just sitting on the top of the bucket. We do not recommend snapping them together.
How does activated charcoal work and how long does it last?
Activiated charcoal works by adsorption which is a chemical attraction of the carbon atoms to impurities in the water. Think of it as the same way a dust mop works on dust. The activation process in the charcoal creates many fissures to greatly expand the surface area of the carbon that is available. Note that it does not work on all chemicals but is works on a wide variety of organic compounds and hydrocarbons. As the charcoal works the surface area becomes clogged with impurities and eventually it is no longer effective. At this point the filter needs to be replaced (usually 6 to 8 months for 4x4 filters).
The filters can be used intermittently with long periods of use in between (such as between camping trips). Simply dry out the filters after use and then store them in a sealed container.
What about accidentally freezing the filter?
Although it is not recommended, these filters have been accidentally frozen and survived with no adverse affects. Repeated experiments with a kitchen freezer have verified that they can withstand freezing, however this is not recommended nor garanteed.
Do these filters need any maintenance?
Yes. If the water flow of the filter decreases the likely cause is the pores in the ceramic filter or sock have become clogged. The filter can be gently 'scrubbed' with a clean non soapy "Scotchbright" pad. The sock can be rinsed in clean water. DO NOT USE SOAP ON THE FILTER OR THE SOCK!!! Note that if the water source is suspected of having bacteria it is advisable to wear protective gloves while cleaning the filter and sock.
Do you accept mail orders?
Yes we do. For the folks who do not like using credit cards we will accept mail orders. Please include the shipping costs along wth the product price. You can determine the shipping rates by adding the products you want to the shopping cart on the site and then adding your zip code. You can see the different shipping options and prices from the drop down menu.
Ship mail order requests to:
PO Box 361
Ponder, Texas 76259
Do you offer bulk buy discounts?
We are constantly asked this question... until recently the answer has always been "No" due to the already low prices (and our slim margins). However we strive to delight our customers with every detail of our product offerings and have added a bulk buy option on a case of 15 emergency filter kits. Why fifteen? It is a small enough size to handle and ship easily, is in the average range of many of our retail requests, and is about the same price as one or two systems from some of our major competitors... If you would like to order larger quantities please send us an email.
Do you work with mission projects?
We absolutely do! Send us an email detailing your needs and we will consider it our privilege to work with you.
We also work with NGO's and other groups that provide humanitarian assistance.
Do you ship internationally?
We ship internationally on special request; please send us an email if you would like to have a shipment sent outside of the US. Please note that international shipping is really expensive compared to the cost of the products when shipping in low retail quantities. On top of the additional shipping many countries impose value added taxes on the products when they are delivered. The end result is that the price is often more than doubled. We usually ship by US Mail which has the lowest shipping rates but they do not provide tracking numbers since they hand off responsibility for delivery to the postal service in the receiving country.
Can other systems be customized?
Definitely! The reason we sell stand-alone components in addition to standard kits, is for do it yourself folks who like to think out of the box. (We would love for you to email us pictures of your set ups.) Here are a couple pictures to give some examples and ideas:
At left is a kitchen table model used to filter tap water.
It uses a low-cost container bought from a local store
along with a single replacement filter bought from our site.
Here is a high capacity unit (three filters
and a pressurization bucket/ kit from our site)
This system is designed to quickly fill
5 gallon containers with pure drinking
water using a lakeside location and a
little air pressure.
(We have recently added this kit to our product offerings as a 'water barter' system for the enterprising preppers out there...)
Here is a 'separated' bucket system. This allows for a much longer siphon height and a lot faster flow rates (up to 10x) over a simple drip system with no siphon. Note that the bottom bucket is still covered to keep the filtered water from getting recontaminated.
The long siphon (6 feet) is a new product available in the components section.
Here are some pictures of lake water treated with these filters:
Water Source - Sikes Lake, Wichita Falls, Texas
Unfiltered water magnified 100x
Same water after ceramic filter magnifed 100x (particles are activated carbon dust from the
new filter used as a focal point)