I live in a rural setting and my water supply is held in a large rectangular concrete holding tank. To check water level I must lift a heavy concrete "door" on the top of the tank. I´d like to replace that door with one made from a painted steel angle iron frame with an eighth inch aluminum sheet bolted in to it. The door will not be imersed in the water it will be over it. Will steel and aluminum together or aluminum alone produce an oxidation that could enter the water and produce a health risk (when used as drinking water)? The water is passed through a household filtering system before consumed.

There are people that believe that aluminum cooking ware causes Alzhiemers (sp) disease. So I think I would check some of the hospital sites on the internet and get their views.

There are people that believe that aluminum cooking ware causes Alzhiemers (sp) disease. So I think I would check some of the hospital sites on the internet and get their views.

No sooner said then done.
Here's a report on the health effects of aluminum.
The only problem is that I don't know if a aluminum cover that doesn't touch the water would fall under the perimeters of the report.

Health effects of aluminum
Aluminum is one of the most widely used metals and also one of the most frequently found compounds in the earth's crust. Due to these facts, aluminum is commonly known as an innocent compound. But still, when one is exposed to high concentrations, it can cause health problems. The water-soluble form of aluminum causes the harmful effects, these particles are called ions. They are usually found in a solution of aluminum in combination with other ions, for instance as aluminum chlorine.

The uptake of aluminum can take place through food, through breathing and by skin contact. Long lasting uptakes of significant concentrations of aluminum can lead to serious health effects, such as:

- Damage to the central nervous system
- Dementia
- Loss of memory
- Listlessness
- Severe trembling

Aluminum is a risk in certain working environments, such as mines, where it can be found in water. People that work in factories where aluminum is applied during production processes may endure lung problems when they breathe in aluminum dust. Aluminum can cause problems for kidney patients when it enters the body during kidney dialyses.

Inhalation of finely divided aluminum and aluminum oxide powder has been reported as a cause of pulmonary fibrosis and lung damage. This effect, know as Shaver’s Disease, is complicated by the presence in the inhaled air of silica and oxides of iron. May also be implicated in Alzheimer’s disease.

If you are worried about it, consider anodized aluminum. Like chroming steel, anodized aluminum is coated with a chemically-bonded, low reactivity substance on the outside. Not only will there be less chance of contaminating your water, the lid should last longer as well.

If you are worried about it, consider anodized aluminum. Like chroming steel, anodized aluminum is coated with a chemically-bonded, low reactivity substance on the outside. Not only will there be less chance of contaminating your water, the lid should last longer as well.

Not having the knowledge I should have I shouldn't even be commenting on this but my gut tells me you're going to be fine cheers, Tom

Thank you all for the helpful responses. I also thought of bolting a sheet of 1/8 inch polypropaline to the underside of the aluminum but the stuff is expensive here.