[Space monkey]

 If I strapped in a 450 Lt tank into the back of my van is that classed as a notification when getting van insurance ?

[harleyman]

You mean modification

[harleyman]

I'd feel a lot safer with it bolted down personally. I wouldn't feel safe  other wise.

[Dry Clean]

A modification is anything that changes the vehicle, just drilling a hole in the floor would be a modification a tow bar being another, for insurance purposes anything that would make the vehicle less safe/roadworthy or more prone to being stolen is what you need to watch out for, so to answer your question I would say no. 

[Lee GLS]

It depends on the insurance company, but even if it’s stopped in using the vehicles tie down points you have to let your insurance company know which I think is ridiculous because you are using your vehicle to transport something just like any other trade, but because it’s a water tank the class it as a modification even if it’s not bolted in.

[EandM]

It depends on the insurance company, but even if it’s stopped in using the vehicles tie down points you have to let your insurance company know which I think is ridiculous because you are using your vehicle to transport something just like any other trade, but because it’s a water tank the class it as a modification even if it’s not bolted in.

Exactly that.

Every Insurance Company has a different set of risk parameters.
One company told me that If I took my truck off-road it would void my insurance - the next company wasn't really bothered at all.
Several companies wouldn't insure a water tank in the back if it was bolted down and others wouldn't if it was.
All wanted any modifications to be disclosed - some refused to insure because of them,  or wanted a large premium loading and the company I ended with didn't mind at all - as long as all the mods were declared

The only consistent thing I learned was - Ask and hopefully engage in dialogue.
I use Gladiator as they're very good at reasoning and don't stick to the script.

[֍Winp®oClean֍]

A tank strapped in isn't a modification. 
If an insurer asks specifically whether you carry a strapped in tank then that's a different matter but strapping a tank into a van does not modify anything at all.

[EandM]

A tank strapped in isn't a modification. 
If an insurer asks specifically whether you carry a strapped in tank then that's a different matter but strapping a tank into a van does not modify anything at all.

I've had a 'modification' classed as ANYTHING the vehicle didn't have when it left the factory.
I once had to argue that the tank not strapped down in the back of my pick up was in fact payload and no different to a wheelbarrow. It was a fairly pointless argument and the company wouldn't shift its attitude.
Fortunately, the next company was a lot more reasonable, though it does make you wonder how far the first company would have gone to not payout on any claim.

Never underestimated the pedantry of an insurance company and never assume anything.
Just ask and hope you avoid any sticky questions with them.
If you don't like the attitude of the company - just find another.

[Lee GLS]

A tank strapped in isn't a modification. 
If an insurer asks specifically whether you carry a strapped in tank then that's a different matter but strapping a tank into a van does not modify anything at all.

It’s not a modification, but as soon as you tell them you are a window cleaner, they ask if you carry a water tank, they then class it as a modification regardless less of wether it’s strapped or bolted in, I’ve had many arguments with insurance companies about this but they are the rules that they have made up and it’s not for us to change their minds. It’s make no sense.

[windowswashed]

Some insurance companies don't like to insure 650 litre water tanks and above, but fine under that weight limit.