True friendship is drinking your best pal's urine.
Well, you can do that if you like, but we're dealing with greywater here.
The milky-coloured ooze that goes down your bathroom sink and shower drains. Technically the kitchen sink ooze is also greywater, but some people call that blackwater.
Brown water.
Also yellow water.
Don't recycle these please.
Van life people are a bit crazy so they tried a few things already. Have any died from it? We will never know, because the dead ones can't make videos about it.
Remember Legionnaires disease?
The most common system, and also commercially available as portable shower systems. You fill it up with water, the water is pumped around and around like a bath, and you re-fill it with fresh water if needed to rinse.
Some systems include some safety measures such as a UV light or small (1 micron or less) filter to remove bacteria. If you don't have these, it's a good idea to shower with the drain open initially to remove the scary stuff. Then refill with water and recirculate once the worst of the bacteria is washed away.
Shower drain
|
v
Mesh filter
|
v
Pump
|
+---- Accumulator (to reduce surging from pump)
|
v
Ceramic filter, preferably << 1 micron
|
v
Optional UV light for sterilization
|
v
Shower head
Advantages: easy to build, available pre-made, little to no concern about bacterial build-up in the system since you start with fresh water every time. You can disinfect the system before/after each use with bleach if desired.
Disadvantages: Only really suitable for showering, as storing and reusing this water would cause it to go rancid. You also shower in your own waste to some extent. But it's true of a bath too.
Conclusion: Not very useful unless you want really long showers and otherwise don't use a lot of water for hand washing, drinking and cooking.
Also called a recirculating shower confusingly, the name comes from a university project to produce a filtered recirculating shower system.
Many van life people have installed similar systems in their vans. Each system is slightly different but the basic principle goes like this:
Shower drain and bathroom sink drain
|
v
Tank <--------------------------------------------+
| |
v |
Mesh filter |
| |
v |
Pump |
| |
+---- Accumulator (to reduce surging from pump) |
| |
v |
Fibre/cloth sediment filter |
| |
v |
Carbon (activated charcoal) filter |
| |
v |
UV light for sterilization |
| |
v |
[You should put a << 1 micron bacteria filter |
here, but most people don't bother] |
| |
v |
Water heater |
| |
+-------> [Solenoid valve to recirculate water >-+
| every hour (most don't bother)]
v ^
Shower head and |
bathroom sink tap 12V timer
Some people make their own filters, most just buy commercial filter cartridges.
Most van lifers change the water only once a week. Their thinking is that the filters remove all the nasties and a lot of the soap.
I have serious doubts about this system. The warm filters full of waste products are perfect breeding grounds for bacteria. The UV light won't work very well once the water becomes a bit cloudy. Legionella bacteria will grow rapidly. Any bacterial waste products secreted by bacterial activity won't be effectively removed.
That said people seem to get away with it! Some have even tested the water and found it OK. Probably depends on luck.
You could add a << 1 micron filter as the last stage to remove bacteria. But it won't remove the waste products. May be OK if you can be sure you won't ingest any of the water by accident. You may find a filter this small gets clogged more quickly.
You'll want a timer connected to a solenoid valve to periodically circulate water through the system. It prevents the water going stagnant inside the filters and pipes. Most people don't bother, but it makes it a bit safer.
If you have separate bathroom and kitchen sinks, use this system for the bathroom only. You cannot put kitchen waste into the tank. Brush your teeth only at the kitchen sink.
To wash dishes, you'll need warm water. The kitchen sink should be supplied with water from both systems. Cold drinking water and warm recirculated water. Wash the dishes using the warm water, and then give them a rinse using drinking water to remove any nasties in the warm water.
The kitchen sink should drain outside or into the sewage tank. That means you'll gradually lose the water in your recirculating tank. Top it up using a valve from the drinking water system. This also keeps the water gradually changing and prevents build-up of soap.
Here is a more complicated two-sink system:
Shower drain and bathroom sink drain
|
v
Overflow to <--------< Tank <--------------------------------------------+
outside if | |
tank too full v |
Mesh filter |
| |
v |
Pump |
| |
+---- Accumulator (to reduce surging from pump) |
| |
v |
Fibre/cloth sediment filter |
| |
v |
Carbon (activated charcoal) filter |
| |
v |
UV light for sterilization |
| |
v |
<< 1 micron ceramic bacteria filter |
| |
v |
Water heater |
| |
+-------> [Solenoid valve to recirculate water >-+
| every hour (most don't bother)] |
v ^ |
Shower head, | |
bathroom and kitchen 12V timer |
sink hot taps |
|
|
Drinking water tank |
| |
v |
Pump |
| |
+---- Accumulator (to reduce surging from pump) |
| |
+-------------> Valve for topping up >-----------+
| recirculating tank
v (manually operated)
Kitchen and bathroom
cold water taps
Advantages: No need to waste precious drinking water for hygiene. You can use the water for hand washing as well as showering. Showers of unlimited length as the water is treated in real-time. Simple low-tech filters which are cheap and easy to replace or clean. By heating the water in the loop, you have a hot water system with no extra complexity.
Disadvantages: Questionable biological safety. Filters don't remove all of the soap so the water becomes less clear and fresh over time. The water shouldn't be used for the final rinse of dishes or for brushing teeth. It's not safe to drink (even if the bacteria is killed there are still chemicals in the water). You will need two independent water systems in your van: wash water and drinking water. You may need disposable plates, cutlery and cups. Otherwise the bulk of your drinking water use will be topping up the tank after washing dishes.
As above but the water heater periodically blasts the entire loop to over 60C. This kills most bacteria. Some like botulinum may survive but aren't very dangerous. The very dangerous waste products secreted by botulinum are denatured by the heat.
This system requires some kind of controller. A simple timer may be enough. Otherwise you may need to programme an Arduino or similar.
The controller should heat the loop a few times a day. It should recirculate the water through the entire system using a bypass solenoid valve. It should detect the water being used. If it's been used recently, it should do a heating cycle to stop any new bacteria in their tracks. Even when it's not actively heated, it should recirculate the water once every hour. It prevents the water going stagnant at any point in the system.
60C water causes scalding. You won't necessarily know how hot the water is at any time. Here are some ideas to reduce the risk:
Advantages: Biologically safe.
Disadvantages: Control system needed. You're still not cleaning the water perfectly. Energy intensive because of the heating. Probably OK if you live in your van. But wastes a ton of energy if it's for occasional use. It has to be heated several times a day no matter what! You can drain the system but you'll never get rid of dampness in the filters. Once bacteria takes hold it'll secrete all kinds of waste. You can't really sterilise the system for storage, botulinum can withstand massive temperatures. All you can do is stop it breeding to dangerous levels, something I wish you could do to Karens using a water heater.
You can try pumping ozone from an ozone generator through the shower loop. Recirculate it a couple of times an hour. But this seems to be pretty dangerous. The ozone gas can be a big problem if it's released. You could die. It could rust your van through. It could attack all the materials in the filters and pipes. You'd need a big UV light to break down the ozone before it reaches the tap. Then the water will be full of disinfection by-products, most of which are toxic. May be OK for washing your hands, definitely not OK for showering with all the particles airbourne!
You'd have to test with the soap you intend to use. What sort of compounds are produced in the water?
Advantages: Nothing grows in the system. Low energy use (ozone generators only need a few watts, only runs twice an hour).
Disadvantages: Disinfection by-products may be more dangerous than the bacteria. Ozone is very dangerous and destructive. Unproven technology in this application. And we know the damage unproven technology can do when deployed. The last few years should have taught you that!
Similar to the above, but you run the water through a copper-silver ion generator instead of the ozone generator.
These generators are sometimes used to disinfect swimming pools. They are also used in some drinking water systems as an alternative to chlorine.
They are usually used with clean water. I don't know if they'll work with soapy water. They may produce by-products used this way. Experimentation and testing is needed.
Advantages: Growth of bacteria is inhibited. Low energy use (ion generators only need a few watts, only runs twice an hour). Probably less by-products produced than ozone. Won't destroy your van or the seals and pipes.
Disadvantages: Unknown if it'll work with soapy water. May produce by-products or just not work when used with soapy water. Silver-copper-ion units are said not to remove some organics, definitely combine it with a suitable << 1 micron filter.
The classic but most energy-intensive method to produce pure water. It works with any quality of input water. You simply boil the water and condense the steam back to water again. Sewage? No problem! (except the smell)
The water may contain traces of alcohol and other liquids which boil at a lower temperature than water. So it is advisable to discharge the first batch of steam leaving the system to outside. This will lose some water but hopefully not much.
If you intend to burn fuel specifically for distilling the water, you'll need a lot of fuel. At least 10-20% of the volume of the water produced. 25 litres water use per day? 20-40 litres of fuel a week!
But there's another way. If you do a lot of driving in the van you may be able to use the waste exhaust heat to boil the water. There is a surprising amount of waste heat leaving the exhaust (about 1/3rd the thermal energy in the fuel burned).
Some care is needed to ensure exhaust gas will not contaminate the water being boiled. Some places also have stupid nanny-state regulations on tampering with the exhaust system which might get you.
Processing speed is slow. You'd need about 0.7kWh of energy to convert 1 litre of water to steam. You could recover some energy by condensing but the system gets complicated. If your van gets 25mpg, you burn about 1.7kWh of fuel every mile. The exhaust carries about 1/3rd of that energy. If you can recover half that, you have 0.3kWh per mile. So you can produce about a litre of water for each two miles you drive. If you do 30 miles a day, you get 15 litres. That might be enough.
Advantages: 100% water recycling. Uses no extra energy (unless you are driving more just to treat water). The water should be clean enough to drink, so you only need one water system in the van. A good complement to a recirculating shower for refilling.
Disadvantages: Requires tampering with the exhaust system. Processing speed may be too slow depending on how much you drive (idling the engine won't produce enough waste heat, forget it). The system may be bulky. Lots of very short journeys won't work well, the engine won't have time to get hot enough.
This German company makes a system which recycles all your greywater back into drinking water. Specifically for camping applications. You'll need a translation programme if you don't know German.
Few people in the van life world know about these. Don't know why. Do they work? Never tried!
Their system uses reverse osmosis. Plus a bunch of other filters. They claim 1000 litres can be recirculated before the system needs refilling with new water. I guess they assume a motorhome has a 50-100 litre tank. That means you can reuse the water 10-20 times.
Using 25 litres a day? You can re-use that same water for a whole week. Impressive!
The systems are very expensive. But I guess they have liability insurance. I'm sure it is fine, reverse osmosis is good.
I would install one of these if they weren't so expensive. I don't know if their filter cartridges are standard. If they go out of business, will you be able to get replacement filters?
A reverse osmosis system in combination with a carbon filter is supposed to remove just about everything from your water. The only catch is that it's slow. You need to process the water over a few hours and store it in a fresh water tank. There are reverse osmosis systems powerful enough to filter water in real-time. But they are extremely expensive and physically huge. And their pumps use a ton of power.
Reverse osmosis systems are used on sea-going vessels to turn nasty filthy saline sea water with sewage floating into pure drinking water.
You can buy cheap under-sink reverse osmosis systems for filtering tap water. These are low pressure systems so they cannot remove salt from water. They won't pass water through if it's too salty. And we all love our salt.
These systems aren't really designed for treating greywater. They expect ordinary tap water. Will they work on greywater? No idea. There's a risk some nasties might sneak through the membrane or seals. You could add extra filters to reduce this risk. They might clog up faster too. If the water is too soapy, the flow might just stop until the water's changed.
They are so cheap it's worth a try.
This system might kill you! Build it at your own risk!!!
+--------------+
+----------<| Flow meter 1 |<--------------------+
+---------+ :::::: | +--------------+ |
\ Sink / | Shower | | ____________ >--+
\___v___/ +----v---+ | ( membrane )>---+
| | | Accumulator 1 ++------------++ |
+------+-----+ | ___ +->| RO system | +-v-+
| | | | | ++--+-+--+-+--++ | F |
v | __ | | | | | | | | | | l |
+-------------+ | | | | | | | | | | | | | o |
+-->| Grey tank |<-----+ | | \ / | | | | | | | | w |
| | 20 litres | _____ ++--++ | | |__| |__| |__| | |
| | [Mesh]---->--->\ />--->| |>---+--------+ Sed. GAC ACB | m |
| +-------------+ \ / +----+ | e |
| | Pump 1 | t |
| Spin-down | e |
| filter | r |
+^+ | Solenoid | |
| |--| valve Accumulator 2 Air vent TDS meter | 2 |
| |--+ ___ | | +-v-+
+-+ | | +-----------+ +----+ |
^ | | __ | Fresh |<-+-<| |<--+
| | | | | | tank | | ++--++
| \ / | | +-<| 10 litres | | | |
| | ++--++ | +-----------+ | | |
+-+--------------+-------------+--<| |<---+---------+ | | |
| | +----+ | | |__|
| point-of-use | Pump 2 v | Activated
| Legionella | Pump 3 +---+ | carbon
| water | +--+ |--| | | block
v filters v +------------\__ | | |--| | | filter
+---+ +---+ | Diesel |~~| |~~ +-v-+ | (ACB)
| | | | | heater __|~~| |~~ | |
+---+ +---+ +------------/ | |<---------+ |
| | +--+>-----------------+
v v Radiator
Sink tap Shower head
The system needs simple control wiring, like this:
12V (always-on)
|
O
\ Isolator (for draining/maintaining the system)
O
| + +--------+ -
+--------------------#----------------------------------------| Pump 2 |-----+
| Fuse for pump 2 +--------+ |
| Relay 1 |
| C / N.O. + +--------+ - |
+--------------------#---------------------------O O---------| Pump 1 |-----+
| Fuse for pump 1 : +--------+ |
# 3A fuse : |
| / / + coil - |
+----------O O----------------O O--------------\/\/------------------------+
| Float switch 1, Float switch 2, |
| turns off when turns off when |
| grey tank below fresh tank full |
| 1/3rd |
| |
| / 12V + in +----------------+ Neg. |
+---O O-------------| 12V thermostat |--------------+-----------------------+
| Hot water | for fresh tank | | - |
| on-off +----------------+ +--------+ Float switch 3, |
| switch | Switched + out | Pump 3 | turns off when |
| | +--------+ fresh tank empty |
| | | + / |
| | +--------O O----+ |
| | | |
| | | |
| | | |
| | N.C. Relay 2 | |
| +---------------------------O \ C | |
| O---------+ |
+--------------------------------------------------------O : |
| N.O. : |
| +------------\/\/----------------+
| | + coil - |
| | |
| | + +----------------+ - |
| +--------------+-----| Solenoid valve |---------+
| | +----------------+ |
| | Switched + out |
| +----------------+ |
| 12V + in | 12V timer, on | Neg. |
+--------------------| for 1 min |--------------------------------------+
| twice a day | |
+----------------+ |
Chassis / battery -
If you want the water heated, add the following components:
After a certain number of litres fresh water produced, change the water in the grey tank. For a 20 litre tank, about 100-200 litres? Experiment to figure how long you can stretch it.
The water in the system can be heated to hand washing temperature if you like, but then the quality of the point-of-use filter is critical. You'll die if you get this wrong. You might want a UV light in the tank just to make sure nothing grows in the warm water. You can also add one of those silver mesh things to reduce growth.
Warming the greywater tank can significantly increase the speed of the filtration. But don't warm it too much otherwise it will turn into a petri dish. Around 20-25C for the greywater tank and hand-wash temperature (30-40C) for the fresh tank. Stick them next to each other (touching) and insulate around the pair as a whole. The heat from one may transfer to the other. Or you might find the warm water going down the drain is enough.
Do not use ozone to control bacteria in the tanks. And never put bleach down the drains or in the tanks! Chlorine and ozone attacks the reverse-osmosis membrane. You may be able to use a copper-silver-ion generator to keep the tank sterile? To clean the sink, use antibacterial wipes without bleach.
Is it safe to drink the water? Maybe. Let's find out!
Advantages: 100% water recycling. Less risk of bacterial hell. When it's time to change the water, you can refill the greywater tank from a river. You can pipe the little gutter channels around your van's roof into the greywater tank. When it rains, you'll get a change of water. The daring may even try recycling yellow water. But watch out for big pharma in your pee that might not filter out well.
Disadvantages: Is it really safe to drink? Consumes a bit of energy as it takes a couple of hours to recycle the water from a single shower. You still need a big water tank if you want to take long showers. If the water gets too dirty to process, it will no longer flow. Replacement reverse osmosis membranes are more expensive. You can't use bleach to clean the sink or chlorine to disinfect the tanks.