Water with a pH lower than 7 is considered as acidic. A pH of 6 is ten times more acidic than that, and a pH of 5 is one hundred times that of 7, so there is a considerable increase in acidity with every point below neutral on the scale.
It is not harmful to drink or bathe in, though a very low pH can have an aggravating effect on some peoples skin. The most common irritations are that it may leave a blue/green ring around baths and basins, cause discolouration to washing and sometimes adversely affect colour treated and blonde hair.
The main problem is the damage it can do to pipe work and water tanks, in particular the hot water tank, as the heating of the water makes it more aggressive. The water slowly eats away at the tank and eventually holes develop. If your piping is copper your water will have elevated copper levels which can lead to indirect health effects, and acidic water generally contains elevated levels of metals leached from underground deposits.
For this reason where pH is a problem the whole house should always be treated and many building societies insist acidic water is treated before a mortgage is granted. It may also be necessary for the correct running of other filtration on the line e.g. Iron removal and UV units.
How it works:
The cylinder is fitted into the water supply as near to the source as possible so that all the water from that point onwards is neutralised. It should be protected from frost. Water passes into the cylinder and permeates through the pH correction media before passing out into the main water line again. The media dissolves into the water until the pH is raised to 7 or 7.2. Once this level is achieved the water is neutral and no more media dissolves.
It is important for the water to be in contact with the media for long enough to allow proper neutralisation, so the tall cylinder allows plenty of contact time with a flow of 5 gallons per minute. Where there is not adequate height two small cylinders can be fitted in series so the water flows through both before returning into the main water line. If the pH is only slightly low it may be possible to use only a small cylinder but advice should be taken on this.
The unit must be refilled at intervals which vary according to the amount of water used and how low the starting pH level is.