A squeeze filter works, but somebody has to stand there squeezing it, one bottle at a time, and in a household that gets old within a day. Stack the same filter element between two buckets and gravity does the work while you do something else.
This is a thirty minute build and it changes the daily water routine more than anything else here.
Why gravity beats squeezing
- It runs unattended. Fill the top bucket in the morning, come back to filtered water.
- It gives you volume. Ten or twenty litres a day rather than a bottle at a time.
- It is gentler on the filter. No hand pressure forcing water through, which means less stress on the fibres.
- A child can use it. Turning a tap is within reach of anyone; squeezing a filter bag properly is not.
- It separates the two buckets clearly. Dirty on top, clean below, which is the single most important habit in any water system.
What you need
Two elements rather than one roughly doubles the flow rate, which is worth doing if you are supplying more than two people.
Ceramic candle elements have one real advantage for this job: they can be cleaned and reused many times by scrubbing the surface, and unlike hollow fibre they are not destroyed by freezing. They are more fragile to knocks.
Building it
- Drill the element hole in the centre of the bottom of the top bucket. Deburr the edge so it does not cut the washer.
- Fit the element through the hole, gasket above, washer and wing nut below, snug but not overtightened. Ceramic cracks if you force it.
- Drill the tap hole near the bottom of the lower bucket, high enough that the tap body clears the base and you can get a jug under it. About 5 cm up is usually right.
- Fit the tap with a washer inside and out, PTFE tape on the thread.
- Stack them. Top bucket sits inside or on top of the bottom one. The element must hang free in the air inside the lower bucket, not sit in the filtered water.
- Lid on top. Always.
- Prime and test. Fill the top with clean water and let it run through. Check for leaks around the tap and the element. Discard the first full batch.
Running it
The daily routine:
- Fill the top bucket with the least dirty water you have.
- Let it run through. Expect a few hours for a full bucket.
- Draw off what you need from the tap.
- Do not let the lower bucket fill to the element.
Pre-filter anything cloudy. Let silty water stand overnight and pour off the top, or strain it through a cloth first. Silt clogs an element quickly and it is a waste of a filter that should last years. See judging raw water for what to look for.
Clean the element when flow slows. For ceramic, scrub the outside gently with a clean brush or a scouring pad under running water, which removes the loaded surface layer. For hollow fibre, backflush as described on squeeze filter care.
Keep the two buckets apart in your head and in the cupboard. Mark them, clearly, DIRTY and CLEAN, in permanent marker on the outside. Never put the dirty lid on the clean bucket, never dip a jug that has touched raw water into the clean one, never swap them round. Cross-contamination is the way this system fails, and it fails silently.