The article deals with researches of the different factors' impact upon the result of gamma/spectrometric determination of 222Rn specific activity in drinking water during sampling. We determined the impact of the air presence in a sampler, pH of water and temperature regime of the sample storage. We have shown that occasional ingress of air in a sampler considerably (two and more times) decreases the analysis results. The observed dependence of the result decrease (in comparison with the reference sample) on the air volume to water volume relation in the sample is close to the logarithmic dependence. Thus, the 40 ml volume of air in a two-liter sampler gave approximately 10 % lower result of the radon determination in comparison with that in the reference sample. At the same time, the sample acidulation with nitric acid to pH = 1,2-2,5 and a sample single frosting/defrosting cycle did not result in statistically reliable distinction of the result from that of the reference sample.