Water purification - steps required and in what order

[bmAvon]

I'm starting to think about preparing for not having tap water available. A few years ago my part of town suffered from a pump failure, so tap water was only available intermittently for a few days which made me realise how much I took it for granted and how much I'd struggle in the event of a wider and longer lasting interruption of water supply.

I don't live right near a stream so water collection will likely have to come from rainwater. I know what steps I can take to make it safer for drinking, but I'm not 100% clear on how much the order matters (apart from 1) or if I need to use all these processes, or if only some will suffice.

1 - pre-filter larger particles with a Millbank bag or similar.
2 - sterilise the water by boiling, or purification tablets if there are issues sourcing fuel
? - a finer filter such as a British Berkefeld. Should this be done before or after step 2, or does it not matter too much?

Context to the above is that it would be for home as I'm not yet looking for solutions for use while being on the move.

Also, does anyone have any idea how quickly water passes through a filter such as the Berkefeld? I appreciate it can vary depending on turbidity, age of filter etc but a rough range would be useful. I'd need enough for four adults (two cats, two humans), and ideally I'd have the ability to purify more water than we need so I could store some of the excess and help some neighbours.

I appreciate any advice and have already found this forum useful by going over years of threads.

[GeraldTheBonzai]

I have a Berkefield and researched this when I bought it.

1. Coarse filtration - get as much of the initial muck out. To much particulate will impact the ceramic filters.
2. Fine filtration - Berkefield. This will filter out the vast majority of stuff. However it won't filter viruses - they are often too small.
3. Boil. Kills off the viruses. Or any other method that kills off viruses.

Berkefield will do about 2 litres / hour BUT it really depends on getting as much junk out in stage 1. More debris means more clogging up = slower flow rate and more maintenance.

[GillyBee]

The Berkefelds can run with anything from one candle filter to four. Four gives you the fastest filtration rate while one is slowest. So if you are worried about how much water you can clean in 24 hours, use 4 filters.
Plenty US households (and some in Devon post cryptosporidium outbreak) filter all their potable water with a gravity filter (Berkey/Berkefeld) and do not complain about running short.

[Frnc]

Presumably you know how to store water, and are doing that?

I don't know a lot about Birkfelds I'm afraid. You could use Oasis purification tabs after filtration. Should be ok.

[bmAvon]

Thanks everyone, that's very helpful.

Gerald and Gilly - reassuring to know I can get approx. 2l per hour with the berkefeld.

Frnc, I'm not yet storing water but intend to. Probably in the garage. I'll leave space for expansion in case of freezing temperatures and will rotate it.

[Frnc]

Thanks everyone, that's very helpful.

Gerald and Gilly - reassuring to know I can get approx. 2l per hour with the berkefeld.

Frnc, I'm not yet storing water but intend to. Probably in the garage. I'll leave space for expansion in case of freezing temperatures and will rotate it.

Storage tips.

1. Use 10l containers, or 5 if necessary. 25l is too big. 40-60 litres total is plenty for one person. You can survive on half to one litre a day for short periods, depending on temperature and physical activity.
2. Steralise 10l container with 2 Milton tabs. Empty. No need to rinse.
3. Fill with fresh water. Add 2 x 33mg Oasis tablets. Leave lid off for half an hour. Put lid on. This is the water you will store.
4. Store away from light. Should be fine in a garage. I put a bin bag over mine.
5. Repeat every 6 months. I like to do one in September, to eliminate the risk of legionella after the summer heatwaves.

[bmAvon]

I'm glad you mentioned container size. I was going to get 25L containers but have now ordered 10L - I need to think about ease of carrying for my wife, or in case I'm moving them while ill.

I've ordered 6x 10L stackable blue plastic jerry cans (and will add more next year) as well as the Milton and Oasis tablets.

[Frnc]

I'm glad you mentioned container size. I was going to get 25L containers but have now ordered 10L - I need to think about ease of carrying for my wife, or in case I'm moving them while ill.

I've ordered 6x 10L stackable blue plastic jerry cans (and will add more next year) as well as the Milton and Oasis tablets.

Perfect! Good job. 25s are harder than you might think, as they are awkward. You are holding a small handle.