Lake water treatment

rp3703rp3703 Posts: 52Registered Users ✭✭

I know this section is used for solar powered water pumping but I thought I'd use it to ask about off grid drinking water as well. My family has a lake cabin in Ontario Canada that we go to for 1-3 months every summer. In the past we have had to purchase our drinking water in 5 gallon jugs from a local marina. Last summer, some neighbors of ours filled up our 5 gallon water jugs using water from the lake run through this UV filter system http://www.aqua-sun-intl.com/stationary-systems.html . I would like to set up a similar system but eliminate the solar panel and water pump and use my own. That way the pressure pump can also be used to provide water pressure for the shower. Ideally, I would like to just plumb the water filter straight into a separate faucet located at the kitchen sink so that you could just turn it on and fill your glass but I found some info about how it can take 10-20 min for the current mercury bulbs to get up to proper temperature to effectively do their job, so my sink faucet idea will not work. Yesterday, I found some information regarding new UV-C LED’s that reach proper temperature immediately and have a much longer life span than mercury bulbs. Unfortunately it seems that this new technology is only being manufactured by this company http://www.aquisense.com at this point in time. I’m a little apprehensive about adopting new technology that has not have a history of use. Does anyone have any experience with these new bulbs? I would also be interested in hearing about other methods I should be considering for turning lake water into drinking water. Other than boiling it for 5 minutes, I have found no other method that does not require chemicals.

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Comments

  • ramlouiramloui Posts: 101Solar Expert ✭✭
    edited April 10 #2

    UV treatment is a good choice to kill bacteria as long as the water is clear enough for the light to get good transmittance. I would also be worried about the amount of power needed by those lights.

    Another option that would be my preference is reverse osmosis (RO). This technology has been around for decades and is very effective. It can be described as filtration on steroids. The heart of the system is a RO membrane where contaminated water is partially forced through the membrane by a high pressure pump. The water that gets through the membrane is called permeate and is pure water, free of bugs and practically all chemicals (except maybe for very low molecular weight, if present in the raw water). What does not get through the membrane goes to waste.

    The only regular maintenance needed is to replace the RO membrane once in a while.

    Check this site out: http://www.cwwltd.com/residential-under-counter-reverse-osmosis-systems/

    I am in the same situation for drinking water at my cabin. However, I have chosen to haul the 20L jugs instead of purifying the lake water for cost/power effectiveness.

    Good luck.

    Louis R.

    Off-grid cabin in northern Quebec: 6 x 250 W Conergy panels, FM80, 4 x 6V CR430 in series (24V nominal), Magnum MS4024-PAE
  • rp3703rp3703 Posts: 52Registered Users ✭✭
    Well we usually have around 15 or so people on the island at any one time, so needless to say we use a lot of water. I will look into reverse osmosis. I just heard back from the company that makes the LED UV-C bulbs and they will not handle our volume of usage and as expected, they are pretty pricey.
  • BB.BB. Posts: 26,319Super Moderators admin
    edited April 10 #4
    Do you want to sterilize your shower water? Or just sand filter that water (plus chlorine?) and use UV or Ozone to sterilize drinking/cooking water?

    Will you have a cistern (what size) or will this be direct from lake?

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • rp3703rp3703 Posts: 52Registered Users ✭✭
    No sterilizing of the shower water, just drinking and cooking water. The lake water is pumped to an elevated tank(14-16' high) that looks like this http://www.tractorsupply.com/tsc/product/oval-galvinized-stock-tank-2-ft-w-x-6-ft-l-x-2-ft-h-169-gal-capacity?cm_vc=-10005 . Not sure if ours has same capacity. From the tank, water gravity flows to the water heater as well as two sink faucets and the shower. Most large lake particles settle to the bottom of the tank.
  • mike95490mike95490 Posts: 7,058Solar Expert ✭✭✭✭
    We use pond water, and once it's been pumped to a elevated tank, is
    Aerated
    Rough / settling filter
     Slow Sand micro-bio filter https://en.wikipedia.org/wiki/Slow_sand_filter
      built into a 80 gal water tank. Flows 5-15 gpH, and into a 1500 gal storage tank
    Triple-O ozone bubbler in the storage tank   http://www.tripleo.com/

    I have 1500 gal of clean treated water on hand, and less than 50W for the ozone bubbler which uses a UV florescent lamp and a fancy aquarium air pump.
    No chemicals (but also no residual treatment for water stuck in the pipes)  The slow sand filter needs to have water moving through it all the time or the Schmutzdecke  will die and you loose the treatment bio film

    Annual water testing shows good all the time.  Consuming uncertain surface water, I wanted two independent systems that didn't need lots chemicals (chlorine tanks have to be filled and meters verified) or make the water taste bad,  UV systems need 3 minutes to get the light tube to full output, and by then you have filled your glass and drank it !

    UV, ozone, chlorine will NOT destroy Racoon Roundworm eggs, I rely on the slow sand filter to clean them ,
    RO does not sterilize water, and it wastes 200% for each unit filtered.

    So, that's what I've found over the years






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  • ramlouiramloui Posts: 101Solar Expert ✭✭

    Mike,

    You are correct that RO does not sterilize water but it makes it potable.

    Off-grid cabin in northern Quebec: 6 x 250 W Conergy panels, FM80, 4 x 6V CR430 in series (24V nominal), Magnum MS4024-PAE
  • rp3703rp3703 Posts: 52Registered Users ✭✭

    I like the natural aspect of the sand filter but with us only visiting this lake house for 30-90 days out of the year, We would be close to leaving by the time the Schmutzdecke  were to even be fully formed. I have seen filters on youtube that use a special type of mineral that is supposed to lacerate microorganisms to death as they filter through it but I think the manufacturer discontinued selling it(possibly because it did not work, who knows).

  • ramlouiramloui Posts: 101Solar Expert ✭✭
    rp3703 said:

    I have seen filters on youtube that use a special type of mineral that is supposed to lacerate microorganisms to death as they filter through it but I think the manufacturer discontinued selling it(possibly because it did not work, who knows).

    That is probably diatomaceous earth but I would not rely on that to provide me with potable water.
    Off-grid cabin in northern Quebec: 6 x 250 W Conergy panels, FM80, 4 x 6V CR430 in series (24V nominal), Magnum MS4024-PAE
  • jonrjonr Posts: 682Solar Expert ✭✭✭
    Chlorine followed by carbon filters and RO leaves you with sterilized water that is mostly free of all chemicals (including chlorine).   A friend uses it on a batch basis - ie, fill large tank with water and add bleach.  Then it runs to an under-sink RO system.

    If you really don't want chlorine (even if you don't actually drink it), then I'd do ozone in a large tank as Mike does.  Followed by RO.
  • EstragonEstragon Posts: 897Registered Users ✭✭✭✭
    edited April 11 #11
    I'm in NW Ontario and just use filters. A big coarse one ahead of pressure tanks takes out sediment for the whole cabin x-toilets. Fine paper, ceramic, and carbon take out everything else at a point of use tap for drinking water. Toilets fed by raw gravity cistern.

    You should be able to get your water tested by the local provincial district health office. That will tell you what problems (if any) you need to solve.

    Some people at my lake use bottled water, but I've not had any issues with filtered. Some of those people likely don't even drink perfectly good city tap water going by the amount of little bottles of water I seem to see everywhere these days.
    Off-grid.  
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  • rp3703rp3703 Posts: 52Registered Users ✭✭
    Hi Estragon,

    I'm really interested in your set-up since it sounds similar to ours. So you have an elevated tank that you fill with lake water and then use gravity pressure from the tank to push the water through the initial sediment filter? What do you use to get enough water pressure to push the water through the other filters?
  • jonrjonr Posts: 682Solar Expert ✭✭✭
    Be careful of "takes everything out" claims.  I recommend reviewing this:

    https://www.cdc.gov/healthywater/drinking/home-water-treatment/household_water_treatment.html
  • EstragonEstragon Posts: 897Registered Users ✭✭✭✭
    @rp3703 - the gravity tank is only about 25-30' above the cabin, so the pressure isn't enough to go through filters and give decent flow. It was barely enough to get on demand water heating to work, and drinking water water was just a dribble. Likely around 9-10 psi before filters or water heater. I might be able to go another 20' or so in head, but it would need a couple hundred feet of horizontal, or a tower to get there, so decided to add a second system.

    I now use the gravity system seasonally for toilets and hose bibs with no filtering. It works well for that. Toilets take most of the water anyway, sò the main system can be on the small side ( 2x30gal pressure tanks).

    The main water system is a submersible pump through a high volume coarse filter to pressure tanks. Drinking water goes through 3 more filters (small micron paper, ceramic, and carbon) after the pressure tanks.

    I could have also have used the gravity system by adding a small pressure pump and tank downhill from the cistern, but didn't for a couple of reasons. First, the gravity system was seasonal, and I wanted water in winter. The other is the submersible is in deeper (and likely better) water than the jet pump foot valve for the gravity system. The submersible system has a drainback and airtank setup that pushes water below ice level in winter plus a backup heat tape.

    If I didn't need winter water I likely would have added a small pump and pressure tank to the gravity system, with a sediment filter ahead of the tank, and other filters at point-of-use for drinking water, similar to the submersible.

    The filter system works well for me, but my water is pretty good to begin with. You may want to get your water tested by the local health authority before deciding on what is appropriate for your water.
    Off-grid.  
    Main daytime system ~4kw panels into 2xMNClassic150 370ah 48v bank 2xOutback 3548 inverter 120v + 240v autotransformer
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  • LumisolLumisol Posts: 347Registered Users ✭✭
  • rp3703rp3703 Posts: 52Registered Users ✭✭
    Ha Ha! Very Funny! We can all walk down to the lake each morning with our Life Straws and spit into the community coffee pot. No thanks.
  • PhotowhitPhotowhit Posts: 4,002Solar Expert ✭✭✭✭
    Will a ceramic filter work? I think it's the base for a lot of UN and US aid. It will filter out most/all of natural things in North America. It's cheap, effective, and generally slow gravity fed drip like Berkey system, you can make your own with a $10 filter and a couple buckets, provides about 12 gallons a day. you would need several for your crowd, but it's reasonable. A gravity fed sand filter for large particles would keep it from clogging up too quickly.

    https://en.wikipedia.org/wiki/Ceramic_water_filter


    Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Prosine 1800 and Exeltech 1100, ForkLift battery. Off grid for @13 of last 14 years. 1000 watts being added to current CC, @2700 watts to be added with an additional CC.
  • LumisolLumisol Posts: 347Registered Users ✭✭
    rp3703 said:
    Ha Ha! Very Funny! We can all walk down to the lake each morning with our Life Straws and spit into the community coffee pot. No thanks.
    Use the pump version for coffee. ;)
  • EstragonEstragon Posts: 897Registered Users ✭✭✭✭
    I use a thing similar to lifestraw for camping and boating. It beats trying to lug several days worth of drinking water around. I think it makes around 1gal/minute - hand pump version.
    Off-grid.  
    Main daytime system ~4kw panels into 2xMNClassic150 370ah 48v bank 2xOutback 3548 inverter 120v + 240v autotransformer
    Night system ~1kw panels into 1xMNClassic150 700ah 12v bank morningstar 300w inverter
  • PhotowhitPhotowhit Posts: 4,002Solar Expert ✭✭✭✭
    Estragon said:
    ...I think it makes around 1gal/minute - hand pump version.
    You might be seriously off on this, I think my kitchen sink runs less than this!
    Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Prosine 1800 and Exeltech 1100, ForkLift battery. Off grid for @13 of last 14 years. 1000 watts being added to current CC, @2700 watts to be added with an additional CC.
  • Ralph DayRalph Day Posts: 861Solar Expert ✭✭✭
    Canadian Tire or Home Hardware sell Rainfresh systems.  I have a 2 filter (carbon and ceramic) in my house, ceramic in my camping trailer.  They put out enough for drinking and cooking quite easily.  You can put aside a couple of 1 litre jugs in the refrig if you can;t wait or it has to be cold.

    A friend has a gravity feed system north of #7.  It has 2x carbon and ceramic to get the required flow from only 22psi, but works well also.  I don't think an RO system would work with the low pressure you probably have.

    Ralph
  • rp3703rp3703 Posts: 52Registered Users ✭✭
    I'm working on adding 4-5 GPM of pressure with a Shurflo pump, so pressure should not be an issue. 
  • mcgivormcgivor Posts: 784Registered Users ✭✭✭✭
    Gallons per minute is not a measure of pressure it's a measure of volume, although I understand what it is you are trying to explain, just a clarification. 
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  • EstragonEstragon Posts: 897Registered Users ✭✭✭✭
    I suspect the pump will put out ~50 psi. That's how I would have done it - take toilets and lawn service directly off the gravity pipe, then a small pump to filtration.
    Off-grid.  
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  • rp3703rp3703 Posts: 52Registered Users ✭✭
    50 psi is about what I was figuring. Most filter systems need at least 40 psi. So sediment filter at the outlet of the elevated storage tank, run into pressure pump which will "T" to a water heater to create pressurized hot and cold water for a shower,a vanity faucet and the kitchen sink. The cold water supply running to the kitchen sink will run through a 3-stage (small micron paper, ceramic, and carbon) filter. Should I also have a pressure tank to work with the pump? If so what size would you suggest? Yes I know it would still be advisable to get the filtered water at the kitchen faucet tested which I plan to do.
  • BB.BB. Posts: 26,319Super Moderators admin
    edited May 24 #27
    One thing to watch for in your design. While water pumps can output any pressure you need... They have a limitation of how much distance of water they can lift... At sea level pressure that is around 20 feet maximum.

    However, with unfiltered water, you need to put a screen/filter/trap in front of the pump to prevent dirt and sand from getting into the pump parts and valves--And ruining the pump.

    If you have a fine screen/filter and 10' lift... You probably will draw a vacuum and not draw water. Or you create tiny bubbles of vacuum in the inlet which can damage the pump itself as the "bubbles" collapse (cavitation).

    https://en.wikipedia.org/wiki/Cavitation

    Keeping the pump near the water level to reduce lift is helpful. Even better is a submerged pump or a pump the draws water below the surface (inlet through sidewall of tank near bottom of the tank).

    However--When installing a pump+plumbing below water level--You have to make sure that a leak (or failed shutoff float/valve) does not pour water into your electrical system, basement, or wash away soil and collapse your foundation work.

    -Bill

    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • EstragonEstragon Posts: 897Registered Users ✭✭✭✭
    I would put a pressure tank after the pump. Mine is set with a pressure switch to come on at 30psi and off at 50. The advantage is you end up cycling the pump less. The bigger the tank, the less cycling. Aside from wear and tear on the pump, it's also nice that the pump doesn't need to run when someone washes their hands in the middle of the night. Some of those pumps make quite a racket.

    I run toilets off gravity alone. Faucets etc use 2x30gal tanks, which gives about 20gal usable (some of the tank space is air). I would have used bigger, but was limited by space.

    My pump to fill the gravity tank has a screen on the foot valve, and the pump is ~5' above the lake. Like BB said, if you need to filter ahead of the pressure pump, you don't want it to be too fine. Better to keep sand out of the cistern in the first place if you can.
    Off-grid.  
    Main daytime system ~4kw panels into 2xMNClassic150 370ah 48v bank 2xOutback 3548 inverter 120v + 240v autotransformer
    Night system ~1kw panels into 1xMNClassic150 700ah 12v bank morningstar 300w inverter
  • rp3703rp3703 Posts: 52Registered Users ✭✭

    I was thinking about making something like this:

    https://permaculturenews.org/2016/06/20/water-treatment-for-off-the-grid-rainwater-harvesting-systems-water-organizing-modules-woms/

    or this:

    https://secondrain.com/2015/04/16/rainwater-to-drinking-water/

    but the person I’m working with to design this system also wants to add multiple UV lights to out elevated water storage tank to kill everything before it enters the water system. That way we only need to use the UV right after we fill the tank which happens maybe once or twice a week.

  • jonrjonr Posts: 682Solar Expert ✭✭✭
    It's most efficient to filter slowly.  Ie, low pressure and flow to the filter with a pressure/elevated tank after the filter to provide high flow to the faucets.
  • BB.BB. Posts: 26,319Super Moderators admin
    UV light only kills the bad stuff when the light is on.

    So you put the light between the pump and the faucet.

    To protect stored water, the uv light needs to be in the tank and running or cycling (is this even done in real life systems? ).

    Or use an ozone or chlorine or iodine system/treatment for persistent water protection.

    And many people just use a rain water system with no treatment. I guess people can get used to some pathogens in there local water...

    - Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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