And if you've seen the tanks in use at the bottling company, you might decide that a bit of digestive evolution might be a good thing.

Tanks are tanks, folks, whether they're on an aircraft, tucked in the belly of a ship or sitting above ground in a water bottling facility.

A related tale...
 

On one of the tankers I sailed on, we had a problem with the fresh water evaporator when discharging in Lagos, so filled the forepeak potable water tank with fresh water for the ballast passage to Capetown.

The water tasted dreadful but we put it down to the fact it had come from Nigeria. The taste got progressively worse, so on arrival at Capetown pumped the water overboard and despatched an AB with a firehose into the tank to swill it out.

On entering the tank he immediately spotted the problem - the decaying bodies of two stowaways. :yuk:

How many people with domestic cold water tanks in their attics clean their teeth using the cold tap in the bathroom without a thought for what the tank is like.
If they saw inside the tank and the amount of contamination they may change their habits..

Bingofuel
 

Actually the cold water tanks in a house (There are usually two of them) are to feed the (1) The domestic hot water system and (2) The central heating. Any water coming out of the cold tap comes usually direct from the mains without visiting a tank anywhere on the premises.

Passenger aircraft carry tanks of drinking water for use by crew and passengers in flight. The source of drinking water on planes usually is the municipal water supply of the airport where the water is boarded. Water is loaded into aircraft tanks via pipes and hoses from a public water source, or from water tanker trucks.

In the United States, several government agencies share responsibility for the safety of drinking water on airliners.

The Federal Aviation Administration (FAA) oversees maintenance for all parts of the aircraft, including the potable water system.
The Food and Drug Administration (FDA) has jurisdiction over "culinary water" - ice, for example - and the pipes, tankers, or other points at which aircraft obtain water at airports.
The Environmental Protection Agency (EPA) regulates water quality in public water systems, thus it regulates the systems that supply water to airports. EPA also is responsible for the safety of the drinking water on board the aircraft.
Over a period of several months in late 2004, the United States Environmental Protection Agency (EPA) carried out water quality sampling on commercial passenger aircraft. They tested water from galley taps, water fountains, and lavatory faucets.

In two rounds of sampling, a total of 327 randomly selected domestic and international passenger aircraft were sampled. Of those, 49 aircraft (about 15%) were found to be positive for coliform bacteria.

Probably not to be honest.

If the quality of portable water were ever to gain sufficient prominence as an issue then you may find manufacturers modifying the tank designs to improve quality (more filtering, greater ease of cleaning etc).

Until then, it's the same system in the same aircraft.

United States EPA: Aircraft Drinking Water Rule
Health Canada: Aircraft Inspection Program FAQ
Health Canada cautions air travellers with compromised immune systems regarding water quality on aircraft
UK: The Microbiological Quality of Water Onboard Aircraft

Some of you are talking utter nonsense and clearly no nothing about the on load of potable water !

Would you like to expand on that comment HZ123? I see from your biography that you are a Ramp Operations trainer.

The airline I work for does not allow us to serve potable water unless from the boilers for hot drinks.

All cold water we serve comes straight from bottled spring or mineral water.

I know another airline such as Qantas use potable water for the majority of all their services.

I think you will find in the UK only the cold water tap in the kitchen is direct from the mains, traditionally the bath and wash hand basin cold feed was from the attic tank.( with all the associated contamination)
Some modern plumbing solutions are direct feed cold and mains pressure hot with a small header tank to flush toilets, but they are not usual, most plumbers don't bother with attic tanks for flushing toilets if fitting combi boilers, and connect direct to the main feed.

There could be several reasons for that, serving cold water from the tanks requires that you have good quality water in there, which means regular cleaning of the tanks and taking care of where you take in water. Some airports provide water that (though safe) tastes worse than the potable water in other airports. On the other hand, bulk is significantly cheaper than bottled, but supplying only bottled reduces the maintenance required for the potable water system. (Finances may balance out differently domestic vs. intercontinental.)

Bingofuel
 

Not in any of the houses I know. There is no reason to include a tank in the pressure system in the mains supply. this will usually supply all cold taps and WC cisterns. The only deviation from this would be a garden tap which requires a non-return valve upstream of the final faucet to prevent siphon back issues.

My point exactly. The only tanks are usually for gravity fed hot water systems with an additional (steel/plastic) tank to top up the intergral copper tank on the hot water tank. The other tank is to top up any losses in the central hot water system.

So I maintain that contrary to your view, no drinking water passes through a tank in the house, (unless you are in the habit of drinking water from the hot water system).

However we are now getting WAY off topic.

Let us agree to disagree.
Indirect System

An indirect cold water system is when water is supplied to the house at mains pressure, this water is fed directly to a cold water storage cistern via the supply pipe called the 'rising main'. A branch pipe off the rising main delivers drinking water to the kitchen and garden tap/faucet, cold water to all other taps/faucets and appliances is provided indirectly from the cold water storage cistern (not for drinking) under gravity pressure not mains pressure.
The hot water storage cylinder is also supplied with cold water from the same cistern.

Just to add my two penneth

An indirect system refers to the way the water is heated in the hot water cylinder, and NOT in any way to the delivery method of the cold water.

That is of course IMHO based on being a plumber for over twenty years :)

Potable water
 

Small aircraft uses a single water tank of approx 45 US gallons where as a bigger aircraft has 2 tanks to a total of approx 90 US gallons.

The same tank supplies the galley and toilet tap or toilet flushing ( vacuum type).

The galley has a small filter which is changed at a major maintennance check.

The potable water is disinfected with chlorine at a specific scheduled check which is far in between.

The chlorination takes time. It needs a 2 hrs soaking followed by 2 to 3 completed rinsing. Every boiler must be rinsed too. It is done normally in the hanger together with a maintenance check. So it is very unlikely to be done every month. It takes a couple of 2 man hours to dump the 90 gallons water unless you want to flood the hanger floor. The whole process would take over a whole day.

So, short cut is always the way to go in chlorination of potable water. Most of the time, a simple rinsing is carried out after the aircraft is outside of hanger. That explain why the water tastes horrible after a check.

Never in my memory that I have to open a potable tank for inspection in my many years of aircraft maintenance doing numerous C and D checks.

I would not drink the potable water, same as I would not drink the tap from a hotel or cold water from house upstairs. I know what can be inside a tank. It might not make you sick but you may not be lucky every time.

My question is " will the airlines be responsible for a pax off sick after a flight with tummy ache"

Every one has his own degree of immune system. An Indian will not get sick drinking with his own country water, but you as a British will.