Dirty Water water makers

[Trident]

Obviously all the advice is to use clean water out at sea so as not to clog filters and put nasties in to the membranes

Whilst sitting is a tidal river in Cornwall surrounded by brown brackish water and unable to use either of my watermakers it got me wondering if anyone had been able to set up enough pre-filtering to make it work. It was a little frustrating to ration water when I have not one but two machines on board designed to make the stuff. Obviously water from shore was available with a trip to marinas and I could have gone out to sea to run the water maker but I'm curious to hear if anyone has successfully worked around the state of UK rivers

 

[chris-s]

Enough pre-filters of the right granularity will remove most if not all of the solids but will clog up quickly. In my experience of non-boat related ro systems three ten inch prefilters and keep an eye on the tds.

If you are still in the Fal, the Trelissick pontoon just south of the King Harry ferry has free water.

Chris

 

[geem]

Obviously all the advice is to use clean water out at sea so as not to clog filters and put nasties in to the membranes

Whilst sitting is a tidal river in Cornwall surrounded by brown brackish water and unable to use either of my watermakers it got me wondering if anyone had been able to set up enough pre-filtering to make it work. It was a little frustrating to ration water when I have not one but two machines on board designed to make the stuff. Obviously water from shore was available with a trip to marinas and I could have gone out to sea to run the water maker but I'm curious to hear if anyone has successfully worked around the state of UK rivers

220v watermakers can more resilient to making water in water with high particulate. The feed pump on ours is a 250w 220v centrifugal pump. It's mounted below the waterline as the centrifugal pump won't self prime. The great benefit of a large centrifugal pump is they can deal with dirty filters. The pump will ride its curve. A higher resistance to pumping due to dirty filter can be overcome but at reduced flow. An oversized pump doesn't pull much more power than a correctly sized pump until the head pressure is increased. This cannot be done on 12v watermakers as their feed to the Clark pump is critical. Reduced pressure on the feed pump results in reduced pressure at the Clarke pump and low watermaker output.
We have run our watermaker in some terrible water. You need to rinse the filters more often but it's never a problem. We also have a UV filter that filters the water before it enters the tank. A belt and braces additional measure to ensure no lingering nasties

 

[Trident]

Thanks Tim; I'm definitely thinking of a 220v system using the inverter and lithium to power it for that very reason - probably self built rather than bought.

 

[noelex]

I saw an amazing long distance cruising power boat recently with lots of great ideas.

They had a large media filter (like the sand filter used for pools although it contained something more sophisticated than sand from memory ) on their watermaker inlet before the more conventional disposable filters. These media filters are backflushed when cleaning is required so no replacement is needed. It was too large for a yacht, but something similar could possibly be scaled down. There is some discussion of their system on their blog:

Drive by Belting XPM78-01 Möbius 16-20 Aug 2021

The other option is rainwater collection. In the UK we could collect more water this way than we could possibly use.

 

[Trident]

Thanks I’ll take a look I’m we’ll set up for rainwater though it’s not rained in Devon and Cornwall for a month now I’m told!

 

[geem]

Thanks Tim; I'm definitely thinking of a 220v system using the inverter and lithium to power it for that very reason - probably self built rather than bought.

If you want any help, let me know. I built mine 11 years ago. It's been fantastic. I can give a list of kit that works well together. Sizing everything was the difficulty I had when I built mine. Took my a while to suss it out

 

[Trident]

If you want any help, let me know. I built mine 11 years ago. It's been fantastic. I can give a list of kit that works well together. Sizing everything was the difficulty I had when I built mine. Took my a while to suss it out

Thanks - I do

 

[AntarcticPilot]

This may be over caution on my part, but I wouldn't trust water from river or estuary water, even using a reverse osmosis system. Algal or diatom blooms can create some very nasty neurotoxins that are poisonous at very low concentrations; that's why you get warnings not to eat shellfish from particular areas from time to time. They are also non-polar molecules and so potentially "smaller" than ionic species like Na+ and Cl-, even though of higher molecular weight. For the same reason they won't show up on a TDS meter, which measures electrical conductivity. Even if a reverse osmosis system took out 90% of a neurotoxin, there could be enough left to make you unpleasantly ill

 

[Trident]

This may be over caution on my part, but I wouldn't trust water from river or estuary water, even using a reverse osmosis system. Algal or diatom blooms can create some very nasty neurotoxins that are poisonous at very low concentrations; that's why you get warnings not to eat shellfish from particular areas from time to time. They are also non-polar molecules and so potentially "smaller" than ionic species like Na+ and Cl-, even though of higher molecular weight. For the same reason they won't show up on a TDS meter, which measures electrical conductivity. Even if a reverse osmosis system took out 90% of a neurotoxin, there could be enough left to make you unpleasantly ill

Would the Seagul filter (99.999 ceramic filter) remove these after reverse osmosis ? Not my area of expertise though I'll do some research.

I'm very much hoping not to need to do it as we travel but would be good to know we can if necessary

 

[geem]

Would the Seagul filter (99.999 ceramic filter) remove these after reverse osmosis ? Not my area of expertise though I'll do some research.

I'm very much hoping not to need to do it as we travel but would be good to know we can if necessary

RO membranes are super efficient at dealing with bacteria and viruses. The UV works very efficiently with RO as there is so little particulate for bugs to hide behind when being zapped by UV light.

 

[AntarcticPilot]

RO membranes are super efficient at dealing with bacteria and viruses. The UV works very efficiently with RO as there is so little particulate for bugs to hide behind when being zapped by UV light.

The problem I see is that the neurotoxins I mention are released into the water by the metabolism of some microorganisms and are in solution, so a particulate filter won't touch them. The RO will certainly remove them to some extent, but is it enough? I can think of ways to degrade them, but nothing that's routinely available. They break down with time in the environment.

I may be overestimating the problem wildly, but unless certain that organic toxins were completely removed, I'd be unhappy about using RO in confined waters

 

[noelex]

Thanks I’ll take a look I’m we’ll set up for rainwater though it’s not rained in Devon and Cornwall for a month now I’m told!

Unfortunately, large tanks are needed to even out the dry spells if you want to rely totally on rainwater catchment for all your water, even in the UK. But without a watermaker or without being able to run the watermaker (because it is in need of repair or in dirty water), any collected rainwater is a bonus, particularly as it is often much nicer to drink than marina water.

It is a pity that companies producing dedicated cruising yachts don’t more commonly fit such a system. If installed at the build stage it would often be easy to incorporate this feature into the design.

 

[Trident]

I do have pretty good tanks - 900L but after 5 years in the Med with just 300L and becoming very efficient I promised my wife she could have proper showers and a fresh water loo if she came cruising again and that is pretty wasteful! When in clean water and powered by the solar I don't care as it doesn't harm the environment at all but using shore water bothers me as its a scare resource than most people realise

 

[lustyd]

There is a lot of arsenic in the Fal, go to Devoran and you’ll see it quite clearly. I’m not sure RO will remove arsenic (it’s way smaller than water) and the pre filters certainly won’t. Not a big trip to go out to sea once a week or so, the Lizard has much clearer Atlantic water.

 

[Lodestone]

I wouldn't personally draw from these rivers but you'd certainly want an activated carbon filter involved somewhere. On top of Antarctic Pilot's biological toxins there's the local drainage discharge to consider AND possible discharges from mine adits including heavy metals (Lustyd above). Most of the Truro basin drains into...the Truro River but the same would hold true for any of the rias down that way. The Fal looks a bit sweeter up by Ruan Lanihorne but that's dinghy country only.

Just to be dramatic one might say that looks may be deceptive as the Fal flows through uranium country too. If OS is correct it actually shows one of the adits issuing into the Fal. I knew the river flowed through this particular mining sett but I was surpised to see a discharge marked clear as day. Oh and it pays to be careful where one sits in that part of the world. It's all very well to eat your picnic by an engine house and coo over Poldark but you might well be getting a decent dose from the waste dumps.