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Philiboy839 Oct 2013 11:27Hello everyone,
has anyone ever looked into cistern filters for household water reuse systems?
There are manufacturers like Otto Graf and Garantia that sell their own filters, such as the Optimax-Pro filter or the Supra internals, but also companies like 3P Filtertechnik that specialize extensively in this area.
What I find surprising is how many different cistern filters exist, all following roughly the same principle but looking different. Each one is recommended as the best, with the highest possible water yield, and so on. However, it’s hard to determine which filter is more or less suitable for specific situations. Even manufacturers provide limited information, as they naturally try to promote their higher-priced products.
If you check out 3P Filtertechnik, Otto Graf, Garantia, or rewa96, you’ll see what I mean. Filter mesh sizes are specified as 0.30-0.60 mm, 0.30 x 1.7 mm, 0.5 or 0.8 mm. There are surface filters made of stainless steel or plastic, as well as cartridge filters.
This already suggests an important consideration: Can I install a filter with or without a slope? Some tanks do not allow for a slope or a steep slope between inlet and outlet, for example with existing tanks or when the pipe gradient would no longer work otherwise. Of course, the steeper the slope, the better, to flush settled dirt off the filter screen surface as effectively as possible. Provided the filter surface offers enough filtering capacity, enough rainwater also flows into the cistern during heavy rainfall instead of simply running over the filter surface.
Fine or coarse filter surface? Obviously, if you only have leaves, a coarse filter is sufficient; if you have a lot of fine debris, a finer mesh is better. However, a fine mesh tends to clog more quickly and thus creates a sealed filter surface, which causes rainwater to bypass the filter.
In my opinion, an important aspect is surface water drainage. Most cistern filters are designed as closed systems with a siphon overflow, meaning when the cistern is full, water rises inside the filter and runs through the siphon to the overflow. However, fine particles like pollen, which settle on the water surface (as is the case for me), are often overlooked. If this layer is too compact and thick, water turns due to oxygen deficiency. Therefore, the top floating layer must be vacuumed when the tank is full—something 3P has developed very well. But anyone with a plastic tank, like those from Grad or similar, will notice that the tank dome (62.5 cm (24.6 inches)) hardly offers enough space for this.
Have you had experiences with specific filters (any kind)?
has anyone ever looked into cistern filters for household water reuse systems?
There are manufacturers like Otto Graf and Garantia that sell their own filters, such as the Optimax-Pro filter or the Supra internals, but also companies like 3P Filtertechnik that specialize extensively in this area.
What I find surprising is how many different cistern filters exist, all following roughly the same principle but looking different. Each one is recommended as the best, with the highest possible water yield, and so on. However, it’s hard to determine which filter is more or less suitable for specific situations. Even manufacturers provide limited information, as they naturally try to promote their higher-priced products.
If you check out 3P Filtertechnik, Otto Graf, Garantia, or rewa96, you’ll see what I mean. Filter mesh sizes are specified as 0.30-0.60 mm, 0.30 x 1.7 mm, 0.5 or 0.8 mm. There are surface filters made of stainless steel or plastic, as well as cartridge filters.
This already suggests an important consideration: Can I install a filter with or without a slope? Some tanks do not allow for a slope or a steep slope between inlet and outlet, for example with existing tanks or when the pipe gradient would no longer work otherwise. Of course, the steeper the slope, the better, to flush settled dirt off the filter screen surface as effectively as possible. Provided the filter surface offers enough filtering capacity, enough rainwater also flows into the cistern during heavy rainfall instead of simply running over the filter surface.
Fine or coarse filter surface? Obviously, if you only have leaves, a coarse filter is sufficient; if you have a lot of fine debris, a finer mesh is better. However, a fine mesh tends to clog more quickly and thus creates a sealed filter surface, which causes rainwater to bypass the filter.
In my opinion, an important aspect is surface water drainage. Most cistern filters are designed as closed systems with a siphon overflow, meaning when the cistern is full, water rises inside the filter and runs through the siphon to the overflow. However, fine particles like pollen, which settle on the water surface (as is the case for me), are often overlooked. If this layer is too compact and thick, water turns due to oxygen deficiency. Therefore, the top floating layer must be vacuumed when the tank is full—something 3P has developed very well. But anyone with a plastic tank, like those from Grad or similar, will notice that the tank dome (62.5 cm (24.6 inches)) hardly offers enough space for this.
Have you had experiences with specific filters (any kind)?
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