Onboard Water Filtration for Yachts?

start with clean tanks (do what ever is needed to clean them).
after that fill your tanks only through a big activated carbon garden filter (no need to spend a lot of money on marine filters, the active material inside is the same !!)
this will give you very good drinking water and the same time will protect your appliances from Scaling.
make sure you replace the filter twice to 4 times a year, depending on the quantities of water you use.
this is the way I treat my yacht water tanks and my home water system, no plastic bottles on board and an excellent espresso from my espresso machine.
this filtering is the same as the Brita system.
this way was devised and supported by a prominent Professor from the Weizmann Institute who researched the best way for the water system for the laboratories of the institute

Randy- we just use a large Brita tank, and keep it in the refrigerator. Love it.

I'm really against filtering the water before it goes into the tank. Providing you're filling your tank from City water that is treated. I have seen far too many water tanks filled with algae and other stuff from people filtering out the chlorine as they fill the tank. I even saw tadpoles in one. The tank needs some chlorine to keep bacteria and algae from growing in it. I think any and all filtration should be done after the tank.

CPT J,
I agree, I don't pre-filter city water going into the tanks.
We usually carry bottled water for drinking and cooking.
I do sometimes dose the tanks with an occasional shot of bleach to help kill anything in the tanks.

It really depends on how often you're turning the tanks over. Randy is on a large, fully-crewed, vessel- so I'm sure he cycles those tanks a couple of times each week.

At the beginning of each year I fill the entire system with a 10% chlorine to water solution, run it thru all the faucets etc and let it sit over night. The next day I empty the system and refill several times with fresh water. I too use a Brita pitcher in my fridge for drinking water. I have a pre filter for my ice cubes, instant hot water and galley sink. I go thru a lot of water because we use the boat. So it stays fresh, but you may have to repeat this procedure if yours sits for any length of time. You can tell from the taste or slight smell at the bath sink.

we can deplete the fresh water in 2 days.

fresh water limits our time on the hook.

I have a water maker on the dream list.

The more I've seen of water problems, the more I value our watermakers. If we didn't have one, even with a huge water tank, we'd go through it fast.

Gentlemen
I think you never sailed the Med.
You rely on city water to be a clean treatd water.
In Greece, Turkey, Croatia and other remote places in the area,
you'll never know the water quality you get from a tap on marinas, docks and town quays.
we must filter any litre of water you put in your tanks.
It does not frees you from cleaning and care for your boat's water tanks at least once a year!
An activated carbon filter gives you Brita quality water, and filter sand dirt and heavy metals you might find in the water.
Unless you want to use a lot of fuel using your reverse osmosis water maker, I think this the most effective and efficient way to do it.

anybody effectively using a watermaker in the North East US?

We have. We've used one along all US coasts including in Alaska. Did you think there was some unique issue in the NE?

Used one from TX to the Bahamas and up the coast to Maine and back.

Any pre-filter issues with silt in water?
I'm guessing not, by the responses.

Freshwater is what limits my time at anchor.
If I had watermaker I could even do laundry!

If it's silty or muddy you will have to change pre filters more often. Keep an eye on pressure across the filter or suction pressure on the high pressure pump, depends on water maker. First thing after installing the water maker I bought an apartment size front loading washing machine. This was on our sailboat so there was no need for a dryer, enough lines on deck to air dry.

Bobhorn,
thanks, the watermaker just moved up a few notches on the wish list.

No, I used one in the NE with no trouble at all. Even in the Hudson river, unfortunately but had too. Long story.

I think a watermaker is like all the other equipment on your boat. Maintain it well, change filters based on conditions, monitor it diligently. A watermaker is a must have to us.