Want to Build a Charcoal Water Filter

I have been wondering how I can build a charcoal water filter for camping use or on collected rainwater during boil water advisories in urban areas. I have already found one video tutorial By an New-Zealander Youruber showing how to build one with 5 galon buckets, but I guess I would need to "activate" any charcoal I make at home before using it in a water filtration system. I just spent a few extra minutes and found a separate tutorial on how to "activate your charcoal. It looks like I might have to use a good dust mask and work in a well-ventilated area if I need to crush my charcoal as small as the YouTuber in the second video is showing.

Note about the second video: This YouTuber requires purified water for the activation process. There's a good chance you don't have access to purified water if you're trying to build a water filter in the first place. Your best bet may be distilling some water by boiling it or using solar evaporation. He also seems to require lemon juice. The only substitute I can think of is trifoliate orange juice (Poncirus trifoliata). Unfortunately, this plant is only frost hardy down to -10°F, so you may be out of luck if you're allergic to the fruit or live in a climate too cold to grow this plant. I will look around to see if any other acidic plant juice can be used as a substitute.

I am surprised there haven't been any threads on this forum about building a charcoal water filter. I would expect this to come in handy if a homesteader decides to buy an off-grid piece of land with no preexisting plumbing.

First Youtube Video:
https://m.youtube.com/watch?v=G6AwCiQ68KI

Second YouTube Video:
https://m.youtube.com/watch?v=1kySEZxA3Gc

Why a charcoal filter??  Search for sand bio filter here.  The information is here.  Charcoal is only good for chemical removal at low levels and making good quality activated charcoal is tough so most people skip that step and concentrate on building the filter part.  Built correctly and operated properly a sand bio filter is an amazing tool and dead simple to build.

Good news and bad news: The bad news is that it may not be possible to make activated charcoal with lemon juice. The good news is that no lemon juice at all is needed to activate the charcoal. I might still have to do further research to determine if activated charcoal is absolutely necessary for the water filter or if any crushed charcoal will work. I'm a bit worried though that the method the YouTuber in this video is using may not be feasible in a home environment:

Video where a YouTuber compares three chemicals, including lemon juice, to attempt to activate charcoal:
https://m.youtube.com/watch?v=S5Ac8PIfBdY

Video where a YouTube activates charcoal using steam:
https://m.youtube.com/watch?v=GNKeps6pIao

C. Letellier wrote:Why a charcoal filter??  Search for sand bio filter here.  The information is here.  Charcoal is only good for chemical removal at low levels and making good quality activated charcoal is tough so most people skip that step and concentrate on building the filter part.  Built correctly and operated properly a sand bio filter is an amazing tool and dead simple to build.

I want to confirm first if a sand filter can neutralize the pH of rainwater and make it fit for drinking during boil water advisories for municipal city water. The other concern would be filtering out airborn microbes from rainwater or while camping filtering out giardia, amoebas, and fertilized runoff from a stream that otherwise looks clean.

Ryan M Miller wrote:

C. Letellier wrote:Why a charcoal filter??  Search for sand bio filter here.  The information is here.  Charcoal is only good for chemical removal at low levels and making good quality activated charcoal is tough so most people skip that step and concentrate on building the filter part.  Built correctly and operated properly a sand bio filter is an amazing tool and dead simple to build.

I want to confirm first if a sand filter can neutralize the pH of rainwater and make it fit for drinking during boil water advisories for municipal city water. The other concern would be filtering out airborn microbes from rainwater or while camping filtering out giardia, amoebas, and fertilized runoff from a stream that otherwise looks clean.

A sand filter will do almost nothing for pH directly.(longer term a carbon filter is mostly worthless on this front too)  Now you can probably add a limestone layer if your rain is really that bad acidic.  A sand biofilter takes a couple of weeks to begin making water safe from most diseases.  So if you are going to use it during short term boil water orders you need to have been using it right along.  Which would be a pain since you would need non chlorinated water for it to work to kill diseases.  So in the short term it is basically good for sediment removal and a percentage of the bigger bugs and then you still need to treat the water with chlorine, ozone, iodine etc to render it safe to drink.  For camping a carbon filter does absolutely nothing for the air born and water born bugs either.  It will help with fertilizer and heavy metals etc to a limited extent.  But it can overload.  The ideal for camping is a man made light one and know how to build a sand filter if you get stuck somewhere and need to survive longer term.  In a disaster situation the backpack water filter is the short term answer figuring I will need to rig a sand filter for non drinking water needs short term and all water needs longer term.

A sand filter to begin with is mostly for removal of sediments and the bigger disease organisms.  But over time it starts to plug off and filter better.  But more importantly it grows a biosludge in the top couple of inches of the sand.  Thus becoming a sand biofilter.  Because this is a super concentrated feeding area you develop artificially high numbers of predators.  So while the water is working thru this biosludge layer of the sand the predators are eating most of the bugs harmful to you.  When the flow gets too slow you remove some sand and wash it being careful not to completely wreck the sludgy sand in any given location.  You then return the sand  to the filter to run again.  Now to stay healthy it needs to stay aerobic which means fresh aerated water going in on a regular basis.  It also needs a regular supply of biological water to be cleaned to keep the predators healthy and fed.  And of course if you run chlorinated water thru it you kill off the predators and wreck the system.  It can drive it anaerobic and need weeks to get back to producing good water again.  Now if you have chlorinated water and a compost pile you can make humic acid to neutralize the chlorines and chloramines.  When the water stays a bit brown the humic acid  will have made the water safe for you bugs and it is just more food for them.

Now as for you question will regular carbon work?  The answer is yes.  But you need something like 50 to 1000 times as much of it to get the same results.

A boil water advisory is focused on the risk of disease causing organisms in the water. An activated carbon filter adsorbs chemicals, not bio-bits.

Portable water filters designed for extreme situations are typically multi-phase -- a carbon filter for chemicals, then a ceramic filter matrix for most bacteria/amoebic organisms, and then an iodine resin for the smallest bacteria, cysts and viruses.

For most situations in North America, the simple and effective solution is to bring the water to a good rolling boil. My 2c.

Based on the past suggestions on this thread, it sounds like it might not be worth my time to build an activated charcoal water filter. I will start another thread to discuss other water filtration options.

If someone was worried about PFAS in their water supply, I've heard that activated carbon or RO are the only ways to get rid of it.  I have a Berkey filter now but I'm not sure it's doing the trick.  I wonder about adding activated charcoal to the upper chamber to surround the existing filters with.  Might that be a brilliant solution?