Water Filter

[Steve and Karen]

I found a single in-line 2-stage filter that would remove pathogens at the 0.2 micron level (i.e most things that could start growing or living in the tank) coupled with a carbon filter that removes chemicals and improves taste:

MSR Emergency Home Water Filtration System | MEC

Good for 1000 litres of clean water filtration, which translates to about 30 tank refills, or... lots. This would also remove any doubt about whether or not your tank sanitation was good enough in the first place, or that the water quality hasn't degraded since that time, but you still wish to (or have to) drink from the faucet.

Since it's a compression fitting plug-and-play connection at the filter ends, switching out to a new one is easy, as long as you have already solidly tapped into the trailer plumbing like Dave and Linda have. Regular removal for winterizing or non-use for 15 days is necessary. Sterilize by boiling for 3 minutes. Won't play well with antifreeze. There's more here:

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This would certainly eliminate the pesky storage and transport of containers dedicated strictly to drinking quality water. (I had a jug blow out on me recently and soak the galley and the bed.) The only downside I can see is that it may require topping up the trailer tank a little more often, and of course, the maintenance routine; it's not an install-and-forget device. Removing it without draining a small amount of water from the lines into the bin could take some practice.

Since this is meant for home water system pressures, I can't speak to what sort of back pressure this may put on our tiny RV water pump and if it may overly tax it. I may give the project a go in the spring. If it's not a good fit with the trailer from a pressure or maintenance standpoint, I'll have a home backup unit for an emergency. I have no doubts about the 0.2 micron filter making even a pretty nasty tank drinkable again since that is the industry threshold for almost all backcountry filters, though many devices do go smaller than 0.2. However, I still won't abandon my semi-regular tank-cleaning regimen. Starting with the cleanest source, whether it is a stream or the tank, is always the best and makes the filter last the longest.

If you need more clarification or assurances about the difference in pore size and what they filter out, this explains things fairly succinctly: Backpacking Water Filter vs. Water Purifier: What’s the Difference? | MSR

 

[Steve and Karen]

I did get the MSR Home Emergency filter but decided that incorporating it into the trailer's plumbing under the sink was far too difficult, considering the maintenance and winterizing that would still need to take place.

This is what I settled on to make the tank water safely drinkable, if and when we wish a cuppa:

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The Sawyer Mini is a 0.1 micron filter that I have used for backcountry purposes. It will filter out harmful bacteria, cysts and mold spores that have set up shop in your tank through the natural and inevitable degradation of the water quality over time. The 0.1 pore size is too large to trap viruses, but if you sourced your water properly in the first place, there should be none of those in your tank. Most viruses are rarely "free-floating" and routinely attach themselves to particulate matter much larger than 0.1 or 0.2 microns. So, in practical terms, viruses do get get filtered, but the filter companies can't legally make this claim.

Bacteria, however, you have little control over, even with what you may think is a good tank and system sterilization job. This eliminates any concern. It is also superior to a full system filter in that you are only filtering what you drink and not all the water that goes through the trailer's tank. There are other similar setups for home emergency (like the MSR above) and full-size RVs where only the water at the end of the system is treated at the faucet. The Sawyer is designed for a dilute bleach flush before long-term storage, but would be regularly usable throughout a long single trip without any sort of maintenance.

I had to use rubber tubing of 4 different sizes to make the transition. Last one that goes on the faucet is 1/2" I.D. X 5/8" O.D. and provides a snug, but removable fit. The trailer's pump gets the system up to 25 PSI. The filter filaments can likely handle handle this pressure, but it's probably best to run the tap at less than full blast, since it was designed for the lesser pressures of gravity system and back-washing using a large hand-held syringe.