We make another attempt to fix the port fresh water tank.  Our boat has (2) 400 liter fresh water tanks (one on port and one on starboard).  Catana built the painted fiberglass water tanks into the boat back in 2001. 

A few years ago we repainted our built in fresh water tank on the port side. If you recall.  See this blog post “Disgusting Water Tank” we scraped clean and repainted the tank.  Unfortunately, the tank continued to have a slight odor and odd taste despite us following the rigorous potable water paint data sheet. 

We are not sure if it was the paint that did not cure properly or if it was the glue that did not get covered by the paint. 

But either way, something had to be done.

It was time to try again. 

Creating a Larger Access Point

Last time we created a new access point in the center of the tank.  However, we cut it too small which made it very difficult to access the far corners of the tank.

So, this time, we decided to cut a much bigger access point. 

Premik, pictured below, had the honor of cutting the hole, then fiber glassing the edges to hold the new lid. 

It took him about a week to cut the hole, build the edges, and fiberglass them into place. 

Making a New Lid

We took our measurements of the lid and flange to Absolute Stainless. 

They took our precise measurements and instructions and one week later provided us with (2) beautiful lids and flanges.

We ordered our gasket material from Shuk Engineering (SQM 3mm Thick Blue EPDM Rubber Sheet – Potable Water AS/NZ 4020 – 1200mm Wide x 600mm). 

It took about a week to receive the material.

Matt cut the gasket material to match the lid, ordered the screws, and fitted it all together. 

The lid screwed into the flange which was glued and screwed into the top of the water tank.

Preparing the Tank

We decided to try a new paint and went with Jotun Tankguard 412, which is a two-component solvent free tank lining designed for potable water. 

This paint will stick to the International Interline 850 paint that we put on a few years ago. 

However, we do have to scratch up the surface to make it adhere better.  It took about 1.5 days to scratch up all the surfaces in the tank (sides, top, bottom, baffles).  Then the yard did a wax/grease wash to remove all particles prior to painting.

The next big project was completely covering our entire port hallway with plastic lining and pvc. 

Our painter, Damian started to paint the tank by hand and within 30 minutes decided it would be much easier to use the spray gun. 

It took way longer to cover and protect the hallway than it did to paint the tank.  But we really appreciated his efforts to protect our home.

It took about 8 hours spread over 3 days to spray paint the tank.

Now we had to maintain a 23c (74F) temperature while it out-gassed for a week. We ran a dehumidifier (which emits heat) to ensure the hallway had low humidity and stayed warm.  

Preparing for Fresh Water

The tank has to be actively flushed with hot water (100F) and an alkaline cleaner.  I had no idea what an alkaline cleaner was so I had to research what to use for portable water.

We found Five Star PBW (Powdered Brewery Wash) at UBrew4U.  Five Star specifically made PBW for breweries and suitable cleaners for potable water tanks.

We bought (8) of the 1lb tubs which cost about $18USD ($35NZD) each.  We used 4 tubs for each tank 

The process was easy, albeit cumbersome. We carried a 2 gallon bucket to the Norsand Boatyards kitchen and filled it with very hot water. 

We took turns carrying the bucket back to the boat, adding 2.5 tablespoons of PBW, and pouring it into the tank.  Matt and I repeated this process 12+ times. 

Matt used the hose to fill the rest of the tank to the lid.

Matt used our emergency bilge pump to agitate the water and create movement for 1 hour. 

We drained and dried the tank.   Next, we flushed the tank through the pipes and flushed the water tank one more time.  Matt was ready to put it all back together.

The hoses and lines were reattached, the lids all screwed in, the water gauge installed and a new “nipple” or elbow was installed.  Matt then repainted the entire top of the tank to finish off this project.

The Conclusion

We filled the tank with high hopes, fingers crossed and prayers in our hearts. 

Matt and I were pleased with the outcome.  The water tasted and smelled like …. water.  

Repeat the entire process 

Now that we know what works, we repeated the entire process on the starboard water tank. 

We were much better prepared. 

We already had the stainless lid and flange so cutting the new access hole was much easier. 

Since Premik did the port side he was more efficient with starboard.  The fiberglass flange was installed in 2 days.

The next step was the difficult process of removing the old paint.  For the first tank it took a laborer one full week to remove the paint.

Matt borrowed an air needle scaler for the 2nd tank which made the removal process so much easier. 

He started with the old bubbled and flaky paint (top left), then used the gun to remove the paint (top right).  

It took Matt 2 full 8-hour days with the air needle and various scrapers to get it all removed (bottom photos).

We brought Premik in to fill some small cracks. 

Then a laborer came in to sand and prep the surface for paint. 

Damian, the lead painter had the lucky role of spray painting the tank. 

We let it off-gas for a week, cleaned it with PBW, flushed it twice, and had fresh water again!

Our rockstar “glasser” 

The feature image is Premik our premier fiberglass expert provided by Norsand boatyard.

This is Premik contorting his body to fiberglass a potential crack.  He was upside down, backwards, and vertical with Matt holding his legs.

We hike to two different waterfalls and Kauri trees in the AH Reed Memorial Park.  Check out the blog post.

Our blog posts run 8-10 weeks behind actual live events.  We worked on the port water tank in Nov-Dec 2025.