If you are planning to do a scientific study (rather than the pseudoscience that is sometimes associated with 'water clusters' that are supposed to have some mysterious health effect), then certainly you should determine the composition of the water you are dealing with independently. I wouldn't completely trust the stuff the manufacturer puts on their bottles.

But in this case,  the use of commercial bottled mineral  water  as a sample is not a suitable choice due to the unknown number of ions, organic and inorganic chemicals dissolved in the water sample.

You should analyze the water. The ions and other organic/inorganic content are related to the cluster size. The data that is shown by the manufacturers is not accurate enough for a scientific/technical work. 

Yes Prof. This is why i asked the question. To analyze unknown number of ions, organic and inorganic chemicals dissolved in the water is not possible due to limitation of the techniques such as ATS, ICP-AES and others. For example every technique uses a specific wave length and methodology to quantify just one element and in commercial mineral water, there are unknown number of ions, organic and inorganic chemicals.   This is why i said commercial mineral water is not a suitable sample. I think the best approach is to mineralize distilled water and this what i did together with the commercial one.

It is never possible to measure everything in a sample. Experts select the parameters that are important for the purpose.

Can you explain how you intend to determine your parameter "cluster size" and if you intend to investigate if it correlate with anything.

The parameters given on the bottle for mineral water are generally required according to a law or standard. In many cases many more parameters are measured to ensure the safety of the water like full screening for metals by ICP-MS or ICP-OES and pesticide screenings including 100+ specific chemicals. There analysis are usually performed by a certified laboratory and the quality of the data are fine for scientific use.

Prof. Henrik,  the cluster size of water molecules is not a quality parameter and I'm not going to do this analysis to say that this specific treatment will produce water that can cause mysterious health effects. I just want to study the relationship between the cluster size of bottled water and the physical treatment itself, to provide evidence that the physical treatment affects water molecular structure, in order to deduce the relationship between the cluster size and the crystallization mode of water.  The cluster size can be determined by 17-O NMR or Raman spectroscopy. The article will be archived soon and all of your comments are highly appreciated

I would definitely analyze the water chemistry, including alkalinity.  We have found that bottled water chemical composition can differ significantly from the composition on the label, in addition to containing solutes not on the label, such as nitrate (check Perrier - you'll be amazed how much nitrate can be in the bottle!).  Would the cluster size have any relation with the ionic strength of the water?  If so, you would definitely need a complete analysis of major cations and anions (Na, K, Ca, Mg, F, Cl, SO4, HPO4, NO3, NO2, NH4, DOC, and Si).  You'd be surprised what you will find, depending on the brand.  Typically, concentrations of NO2, NH4, and HPO4 are typically below detection.  H4SiO4o, measured as Si4+, can often be a significant solute, again, depending on the brand.  Most brands are calcium-bicarbonate type compositions, but not all.

I would suggest to just 'make' a large batch of your own water with distilled water and added high-purity chemicals.

Alternatively, there are ICP-OES or ICP-MS instruments that allow you to do a semi-quantitative scan for 'all' the elements that are in your samples. After that, you can analyse the ones that appear to be there quantitatively.

Yes, I agree with Marlina, I would suggest to make your own water using pure distilled water. In non-destilled water some ions could be below detection, and they could influence the clusters. The dimensions of the clusters and composition are related to SAR.

Definitively I would suggest   to make your own water using pure distilled wáter, and add the chemicals in the experiments.

The parameters to be examined before applying physical treatments depends on (1) the geological units of that particular area and (2) any anthropogenic inputs to the water. This is because, geological units play the most significant role in controlling level of concentration of water-constituents. For example, fluoride and arsenic concentrations are dependent primarily on their source minerals. Secondly, concentrations of some parameters are affected due to anthropogenic activities. For example, fluoride concentration in groundwater is slightly to moderately enhanced by the use of phosphatic fertilizers. Hence, you must be aware of the expected pollutants (in terms of excessive quantity or in terms of foreign substance) before going for application of physical treatments. Then only can you measure the effectiveness of the physical treatment process!

Professors : Enrique A. Navarro  and Marlina Elburg,  Thank you very much for your reply. Actually in my answers i said "I think the best approach is to mineralize distilled water and this what i did together with the commercial one." 

So i already did what you suggested. Thank you for your reply