Question regarding contacts liquids

[hurly]

Hi guys

I'm currently using daily contacts (the ones that you use one per day and then throw them away).
I'm considering using monthly contacts or 2-weeks contacts. If I do get them, I have to clean them with contacts liquid every night.

Is it safe/good for the eye to just clean them with spring water?
(I live in a country where you can drink from the spring).

I hear that the contacts liquid contains only water and salt.

[JackBean]

The salt is important because of the osmotic pressure.

[hurly]

But water contains salt too doesn't it?
And how important is this osmotic pressure...?

[mith]

cheap salt test: taste the eye cleaning solution and taste the spring water.