Russia leads the developed world with the worst sanitation record, according to the London-based WaterAid NGO. A 2012 estimate citing official data placed the number of Russians whose households are only equipped with outhouses at 35 million, or roughly a quarter of the population.

More than one-fifth of Russian households do not have access to indoor plumbing, according to official statistics obtained by the RBC news website on Tuesday.

Of the 22.6 percent of households without a centralized sewage system, 16.8 percent use a system of pipes connected to pit toilets, RBC cited the State Statistics Service, Rosstat, as saying. The other 5.8 percent lack a sewage system altogether.

In rural Russia, almost two-thirds have no access to indoor toilets, 48.1 percent of whom use outhouses and 18.4 percent do not have a sewage system.

Only 9 percent of Russia’s urban population reported lack of access to a sewage system.

Rosstat carried out the study involving 60,000 households in every Russian region between Sept. 15 and Sept. 29, 2018, RBC reported.

After gradually climbing to 78 percent in 2017, the latest data indicates that the share of Russian households with indoor plumbing slightly decreased to 77.4 percent in 2018.