Thru hull question

We have an IP445. We would prefer not to add another thru hull for our watermaker and would prefer to use an existing one. We are thinking of using the fridge drain thru hull which is currently a 3/4" unit. We would put in a 1.5" thru hull, add a water strainer and add a "T" for the water maker just past the strainer. We would also add a second "T" in line for a washdown pump and then the inlet for the fridge drain.

Does anyone see problems with this? Are we missing anything?

What type/brand of thru hull do you recommend?

Island Dreamer
Yes I have a couple of concerns about your plan.
While I am not that familiar with the IP 445; some frig drains are very close to the water line, and you want the water maker intake as deep as possible. For two reasons – one you don’t want to pick up air bubbles and have them “exploding” thru the membrane. You want to be able to make water underway and the boat can be rolling around in a sea way and can create a lot of bubbles. Second, oil floats on the water, and you will have less chance of picking it up the deeper your water pick up. The oil will destroy the membrane. You will find it very use full to run the water maker briefly at the dock before heading off shore just to check it out before you get away from spares and water maker expert help. Oil or gas floating on the water can be an issue in port. If your frig drain is very deep then these issues may not be a consideration. But if I understand your approach correctly you will still stand the chance of sucking material spilled in the refrig into the water maker. Think “soap or bleach or mayo” none will help the water maker.
Next, where do you plan to install your water maker and the wash down pump? Your planned water maker location is another consideration effecting your thru hull choice. It will affect the location of the filters, boost pump, and overboard drain – 95% of the intake water goes overboard as waste. Is it going to be close to the wash down pump or the close to the refrig? I don’t think you want hoses running all over the boat just so you can use a specific thu hull. Even if you do use the refrig thu hull you will have a supply hose or pressure hose running to the front of the boat for the wash down pump.
My advice would be to add a thru hull for the water maker intake and share it with the wash down if the installation locations make sense. You won’t be using the wash down while making water because you won’t want all the anchor mud in the water maker. What other thru hulls are available to share? Does the boat have air conditioning? If so where does it get its cooling water and reject its waste water? That may be another source. The head intake may also work if it isn’t shared with the engine. As a general rule I am uncomfortable sharing the engine intake because if (when) the strainer gets plugged the motor will suck all the water out of the water maker.
My two cents
George
S/V Delicia IP40

Hayden,
That is great looking installation, the drain plan sounds great. It should be high enough, you will likely make water underway when motoring so you shouldn’t have much heel. Here are a few thoughts about your weekly usage plan - - You might consider running the WM every day. It is far more efficient to run it every 24 hours and never back flush it. That way you don’t waste 5 gallons of fresh water every time you run it. I replaced my first membrane after 7 years never back flushing it, and when I replaced it was still making 310 – 380 ppm water. In fact I have no provision to back flush it. I try to run it once a day and try never to go over 48 hrs. w/o running it. The manufacturer recommends no more than 72 hrs. w/o using or pickling. Even if I don’t need the water, I run it for about 15 minutes, just enough to clear the membrane and start making good water again, then shut it down. There are two other advantages to this operation protocol. 1. You don’t need a carbon filter or the back flush plumbing. 2. It is easier on the batteries – You don’t draw down so much because you have shorter runs. Your unit is much more power efficient than my old 160 Katadyn, so the power issues may not be as important. We use 22 amps for about 7 gal/hr.
As far as back flush and membrane health goes, all the membranes are the same – all made the same way and all covered by the same patent.
George
S/V Delicia, IP40

Sounds very reasonable, go for it.