The basic prin­ci­ples of state pol­i­cy in the field of drink­ing water, drink­ing water sup­ply, and waste­water dis­pos­al are for­mu­lat­ed in the Law of Ukraine “On Drink­ing Water, Drink­ing Water Sup­ply and Waste­water Dis­pos­al” (Arti­cle 6). One of these prin­ci­ples requires “main­tain­ing an opti­mal bal­ance between the use of sur­face water and ground­wa­ter for drink­ing water sup­ply.” But what exact­ly is meant by an “opti­mal bal­ance”? Unfor­tu­nate­ly, nei­ther the law itself nor any sub­or­di­nate reg­u­la­tions or method­olog­i­cal doc­u­ments pro­vide any clar­i­fi­ca­tion or spec­i­fi­ca­tion. Let us there­fore exam­ine the ratio between ground­wa­ter and sur­face water used for pub­lic water sup­ply in Ukraine and in the coun­tries of the Euro­pean Union.

Accord­ing to one of the guid­ance doc­u­ments of the Com­mon Imple­men­ta­tion Strat­e­gy of the Euro­pean Com­mis­sion for the Water Frame­work Direc­tive (2000/60/EC) — Guid­ance Doc­u­ment No. 15 “Ground­wa­ter Mon­i­tor­ing” — the share of ground­wa­ter in pub­lic water sup­ply varies sig­nif­i­cant­ly among coun­tries. For exam­ple, ground­wa­ter accounts for 99% of pub­lic water sup­ply in Aus­tria and Den­mark, 96% in Hun­gary, 94% and 93% in Ice­land and Switzer­land respec­tive­ly, 80% in Italy, 72% in Ger­many, and 62% in France. In Greece and Por­tu­gal, ground­wa­ter and sur­face water are used equal­ly, at a 50/50 ratio. There are also sev­er­al coun­tries where sur­face water pre­dom­i­nates, includ­ing the Unit­ed King­dom (35% ground­wa­ter), Spain (21%), and Nor­way (13%).

Over­all, the num­ber of Euro­pean coun­tries where ground­wa­ter pre­dom­i­nates in the struc­ture of water sup­ply reach­es 65%. The ratio between ground­wa­ter and sur­face water sup­ply is deter­mined by a num­ber of con­di­tions and fac­tors, the most impor­tant of which are nat­ur­al water resources — their quan­ti­ty and qual­i­ty — which depend on geo­log­i­cal struc­ture, hydro­ge­o­log­i­cal con­di­tions, cli­mate, the lev­el of anthro­pogenic pres­sure, and oth­er fac­tors.

In Ukraine, the share of ground­wa­ter in pub­lic water sup­ply is less than 25%, and over recent decades there has been a steady decline in ground­wa­ter extrac­tion. Dur­ing the last 20 years, ground­wa­ter pro­duc­tion has decreased three­fold.

Even in the city of Kyiv, accord­ing to the web­site of Kyivvodokanal, ground­wa­ter account­ed for only 9.5% of pub­lic water sup­ply in 2018 and even less — 8.6% — in 2019. Cur­rent­ly, ground­wa­ter extrac­tion with­in Kyiv amounts to only about 13% of the offi­cial­ly approved exploitable reserves, although these reserves are suf­fi­cient to sat­is­fy 100% of the city’s water demand.

Obvi­ous­ly, using sur­face water for water sup­ply is con­sid­er­ably cheap­er, but how safe and ben­e­fi­cial is it? Sur­face waters are vul­ner­a­ble to con­t­a­m­i­na­tion and may con­tain sub­stances that are not rou­tine­ly iden­ti­fied dur­ing lab­o­ra­to­ry qual­i­ty con­trol. Before being sup­plied to con­sumers, they require dis­in­fec­tion with chlo­rine com­pounds. Ground­wa­ter, by con­trast, is nat­u­ral­ly pro­tect­ed from sur­face con­t­a­m­i­na­tion and under­goes nat­ur­al purifi­ca­tion while fil­ter­ing through rock stra­ta over thou­sands of years.

What can be con­sid­ered an opti­mal bal­ance between the use of sur­face water and ground­wa­ter for drink­ing water sup­ply in Ukraine? Ukraine pos­sess­es suf­fi­cient ground­wa­ter resources, although they are uneven­ly dis­trib­uted across the ter­ri­to­ry. There­fore, a com­plete отказ from the use of sur­face water is nei­ther real­is­tic nor advis­able. At the same time, anthro­pogenic pres­sure in Ukraine remains sig­nif­i­cant. Despite the decline of many sec­tors of the econ­o­my, agri­cul­tur­al pro­duc­tion con­tin­ues to grow steadi­ly. This is accom­pa­nied by the increas­ing use of fer­til­iz­ers and chem­i­cal agents, which inevitably affects the con­di­tion of sur­face waters. It is there­fore obvi­ous that in areas with sub­stan­tial anthro­pogenic impact, it is more appro­pri­ate to rely on ground­wa­ter resources, which are bet­ter pro­tect­ed from sur­face con­t­a­m­i­na­tion.

Thus, con­sid­er­ing the avail­abil­i­ty of sub­stan­tial ground­wa­ter resources on the one hand and the sig­nif­i­cant anthro­pogenic pres­sure on the oth­er, it can be con­clud­ed that for Ukraine the opti­mal bal­ance between sur­face water and ground­wa­ter use for drink­ing water sup­ply would be a 50/50 ratio.