FreedomYachts.org

I suggest that everyone put a couple of stainless deck plates in their water tanks so you can get inside to clean them. Your first time will be a smelly shock. Clean the tank at the start of every season at a minimum. You will be happy you did.
Attached is a picture of the inside of my tank after one season filling at reputable places. This type of inspection port leaks. Use a stainless steel port.

On my 40/40 the tanks are aluminum. What are they on the F30? If they're Al, I certainly wouldn't recommend using a stainless port.

-- Geoff

I've put two of these in the top of my water tank. The original tanks are poly plastic.

Whoops -

https://www.fisheriessupply.com/seabuilt

My tanks are also poly. I have thought about installing inspection ports for quite a while now. I have decided against for two reasons. First, I have not seen any significant "growth" inside the tanks. The water smells OK, etc. Second, I don't use tank water for anything but dish washing and bathing. I use separate 3.5 gallon water bricks for all my drinking water.

http://www.waterbrick.org/shop/

I do have the SS inspection port on my aluminum fuel tank which absolutely does require routine inspection/cleaning. The ports shown in the thread work extremely well. I have not had a leak in six years I've had it installed.

I have removed the holding tank and associated head plumbing from my boat. I never used it. The toilet bowl remains in place. I use wag bags in conjunction with the toilet bowl when I am in-shore. After use these are stored in a container in the lazarette. Off shore I use a bucket.

http://www.cleanwaste.com/go-anywhere-toilet-kit