WATER TANKS

[andywatson]

Although stainless or food grade polypropylene is the modern fashion for water tanks and initially it seems a logical choice I have I have the following thoughts to debate:

 

1 Is stainless more prone to splitting on welds?

I've heard of a few cases of this, other than recently as per Ange's post.

 

2 How many stainless and polyprop tanks have cleaning hatches.

Bacterial growth may still take place unless a regular treatment regime is undertaken.

Unless you can actually get in and see how do you know what's going on in there.

 

3 Seperate tanks obviously cost more.

How much does a stainless tank or polypropylene tank actually cost?

 

4 How much condensation occurs on a stainless talk?

The bulkhead of my integral one gets wet in winter.

Does a seperate tank with a much greater exposed surface area suffer proportionately of does it warm up a bit and get less condensation per unit area?

 

5 How long does the bituminous paint last in an integral tank?

I've had my boat 3 years and due to having to access the tank through the side (Honest!) due to a generator mounted above I've put off cleaning it out. To date I've suffered no ill effects due to drinking the water from it.

I don't even use the filter tap I've got.

 

6 Modern epoxy paints with very long life spans could be used to coat the inside of a integral tank.

Has anyone here actually done this on a new boat?

 

7 Has anyone actually had canal water contamination into the hatch of an integral tank or a leak the other way?

That they are aware of anyway?

 

Well that's a start.

Fire away!?

[Smelly]

A mate of mine's SS tank split a couple of years back, he woke up one morning with 250 gallons of water swilling round. We had a hell of a job getting it out as well. He wasn't a mate when it happened, we'd not long moved here, however He had a need and I had the tools.

 

My SS tank does generate quite a lof of condensation but I wonder whether, if I put the last sheet of ply back up and sealed it it might help, however there's lots of handy storage around the tank.

[Ange]

1 Is stainless more prone to splitting on welds?

 

Our surveyor told us that stainless steel is brittle, and if it is unsupported the tank will expand when it is full, then contract when it it empties. Eventually it will suffer metal fatigue, which I guess is what happened to ours. Dave's dad knows nothing about boats but is a welder by trade and agrees.

[churchward]

I have been on boats with integral and separate tanks. I guess there are pros and cons of each type.

 

I have heard of some stainless tanks splitting I imagine using a better gauge of metal or better bracing could cure this.

 

Our boat at has a separate plastic tank. I suppose that like some plastics it may harden over time and become more brittle but since this mostly happens by ultra violet radiation from the sun it may not be a factor as it is permanently in the dark.

 

Personally I favour a separate plastic tank mainly for the reasons that it doesn't need any maintenance like an integral tank in terms of painting it. An integral tank is strong though and not likely to cause problems but it does need regular cleaning and repainting. However, one thing I would consider if I had a new boat is a flexible liner in an integral tank, which just might be a best of both worlds solution.

[DaveR]

Integral steel tanks give the largest capacity. The Bensham has a 1,000 litre one built in under the fore deck. There is an access hatch which I (6'2" and 100kg) can manage to squeeze through to do maintenance.

 

Have found that if I empty the tank every other year and clear out the small silt and paint it every 4 or 5 years than the water quality is fine. No taste, no discolouration no bugs. I don't sanitize the system or have filters in the discharge pipework. I do take care to make sure the fill hose doesn't go into the cut or be dragged through the grass etc. before filling as that can be the source of many a bug.

 

How you clean the much smaller stainless or plastic tanks is never considered, anyone who thinks our water is completely clean and clear obviously has never looked into the tank in the loft recently.

[churchward]

How you clean the much smaller stainless or plastic tanks is never considered, anyone who thinks our water is completely clean and clear obviously has never looked into the tank in the loft recently.

 

True, the loft supply tank is likely to have a layer of silt in it over time. Although strictly speaking you are not supposed to use it for drinking supply as drinking water is supplied direct from the mains.

 

A seperate water tank on a narrow boat is more or less a sealed unit and so any sediment brought in could/will build up. However as long as the water is not contaminated the sediment is likely to remain inert. You can of course use flushing/sterilising agents periodically to refresh the tank. I suppose also it depends on how much you use the water in the tank. If you are a live aboard you will be using the tanks contents regularly and fresh water will be replaced often. If you only us ethe boat a couple of holidays a year or so then the water in the tank is retained for longer and potentially cause problems but that will be true no matter wich type of tank you have.