In order to assure the analytical quality, internal "dummy" and interlaboratory  cross-check  samples are analyzed regularly  by the Water Chemistry Laboratory (HU WCL).  
The following table compares the results of the analyses of  an interlaboratory comparison sample provided by the Isotope Hydrology Laboratory of the International 
Atomic Energy Agency. Results are given in meq/l units. 
| LABORATORY | Ca | Mg | Na | K | Total Cation | 
| IAEA | 2,32 | 0,78 | 0,88 | 0,06 | 4,04 | 
| HU WCL | 2,582 | 0,720 | 0,709 | 0,078 | 4,089 | 
| LABORATORY | CO3 | HCO3 | Cl | SO4 | Total Anion | 
| IAEA | 0,00 | 2,74 | 0,86 | 0,25 | 3,85 | 
| HU WCL | 0,111 | 2,942 | 0,790 | 0,255 | 4,098 |