Water Purification Systems

Like many 'services' on Lasqueti, domestic water supply is a do-it-yourself affair for most of us.   Typically shunning drilled wells, many households rely on rain-water collection in cisterns, shallow wells, or open ponds to supply water to their homes.   Surface and stored water sources can harbour nasty bacteria, viruses, and cysts that may cause waterborne illness, ranging from the unpleasant to the lethal.

I asked Lasquetians how they treated their domestic water… this is what I found.
(** Caveat emptor: this article makes no recommendation and should not be interpreted as advice.)

Multi-stage Filtration

There are a wide range of water purification technologies in use on Lasqueti, but the constraints of this lifestyle appear to favour water filtration systems.    A variety of different filtration systems in use on Lasqueti are documented below, but one strategy common to many systems is “multi-stage filtration”.

A typical multi-stage filtration system might have these components:

  1. intake screen;
  2. sediment screen or ‘irrigation filter’;
  3. sediment filter;
  4. drinking water filter
Stage 1: Intake Screen
  • A rough screen on the water intake to filter out larger solids - typically filters out solids greater than 1 mm
  • Should be cleaned periodically by reverse flushing, or just hauling it out and brushing off accumulated crud.
  • Simple, cheap, and effective to keep debris from entering your system in the first place.
Stag 2: Sediment Screen / Irrigation Filter
  • Typically a cylinder or disk with a fine mesh that uses water pressure to filter out solids larger than 150 - 250 microns.
  • Screens out sand, sediment, algae, and other small particles without reducing the pressure.   
  • These screens are very easy to clean and cheap to replace.  A cheap, effective way to keep drip irrigation and watering systems from clogging up, and to extend the lifespan of your down-stream filters.
  • Water at this stage is suitable for gardening and flushing toilets (as if you had such a thing :-). 
Stage 3: Sediment Filter
  • Typically a 5 - 30 micron cartridge filter removes all but microscopic particles from water.  Some water pressure is required, but not much.
  • These filters are readily available and the filter cartridges are generally quite cheap to replace, thus making them an effective way to extend the lifespan of your downstream filters.
  • This step als significantly reduces the 'load' of nasties, which often 'hitch a ride' on the larger particles filtered out at this stage.
  • The water exiting the filter is clear and clean (but not yet suitable for drinking or washing fresh food).    Water at this stage is well-suited to doing laundry and other cleaning chores. 
  • Although the CDC would definitely recommend against it, this water is often plumbed directly to showers and sinks.
Stage 4: Drinking Water Filtration Systems

This is where the bulk of my research was focussed.  Below I document the pro’s and con’s for 4 systems in common use on Lasqueti.

  • WaterSprite:  http://watersprite.ca/
    Distributed right here on Lasqueti by our very own, WaterSprite offers 2 distinct solutions, both of which use a Doulton Ceramic Filter.  These filters can be cleaned and have a long lifespan.  WaterSprite is local and offers free shipping in Canada.  All the feedback I received from WaterSprite users was positive, and you are supporting a local business.

    •  WaterSprite Gravity System - a countertop filtration and dispensing vessel
      Pros:  no water pressure required;  water can be sterilized (i.e. boiled) before filtering
      Cons: not a ‘running water’ source
    • WaterSprite Counter-top / Below Counter Systems - a ceramic cartridge filter and faucet
      Pros: flexible, multi-stage purification with up to 4 different filtration media;  sink-mount faucet
      Cons: requires water pressure;  ceramic filter needs to be cleaned ~ once/month or more
  • Activated Carbon Block
    e.g. Multipure: http://www.multipure.com/

    The best of these filter to 0.5 microns, which is sufficient to filter out small cysts (like cryptosporidium), but this not true for all carbon block filters.  Carbon filters tend inhibit growth of bacterial inside the filter medium, and with a pre-filter, these filters can last up to a year without maintenance.

    • Pros:  works with moderate water pressure;  removes common contaminants (organic chemicals, heavy metals, etc.);  anti-bacterial;  low-maintenance
    • Cons: varying quality and availability — look carefully for NSF/ANSI certification, along with cost and availability of replacement filter cartridges first.
  • Dual-cartridge carbon / ceramic filter
    e.g., RainFresh: http://www.rainfresh.ca/

    This was the system I received the most feedback about, all of it positive.  This system uses a 3-stage filter - activated carbon block to remove sediment & odour; 0.3 micron ceramic to trap the nasties; with an activated carbon core, presumably to retard growth of bacteria in the ceramic filter media and ‘sweeten’ the water.

    • Pros:  Canadian company;  locally available at several outlets in P’ville and Nanaimo;  relatively inexpensive filter cartridges
    • Cons: requires significant water pressure;  ceramic filter needs to be cleaned ~ once/month or more
  • Reverse Osmosis
    https://en.wikipedia.org/wiki/Reverse_osmosis

    These systems are also typically multi-stage, with 2 or more pre-filters, a reverse osmosis membrane, and typically a post carbon block filter, presumably to ‘sweeten’ the water.   These systems may be impractical for many because they require substantial pressure (> 40 psi), and only utilize 25% of water (i.e., they produce 3 litres of ’waste water’ for every 1 litre of purified water, although that waste water can be re-captured and used for watering, etc.).

    • Pros: removes virtually all contaminants, resulting in nearly pure H2O; deionized so can be used in batteries;
    • Cons: water is de-mineralized; higher maintenance and costs;  requires substantial water pressure;  25% water-use efficiency;

Finally, I received a recommendation for an online water purification business that sells variations on many of the above and more.  For posterity:  https://www.watercheck.biz/products

** Caveat emptor:
This article in no way should be seen to be recommending a specific system or advising on adequate sanitation for drinking water — it is intended only to document the current state of water purification technology, as applied on Lasqueti.  
Ideally, all your domestic water would be purified to NSF Drinking Water Treatment Standards.  For most, a lack of reliable power, water pressure, and/or infrastructure makes that impractical.  This article simply documents some of the strategies employed to cope with this reality, while meeting daily needs for a domestic water supply.