San Francisco's Catholic Cathedral installed a special sprinkler system to wash out "needles, feces and other dangerous items" from its doorways, a senior cleric has said after the church was criticized for being unfriendly to the poor.

It was never intended to remove homeless people sleeping there, the archdiocese explained following criticism levelled at the church in some media, Catholic News Agency reports.

"The problem was particularly dangerous because students and elderly people regularly pass these locations on their way to school and Mass every day," San Francisco Auxiliary Bishop William Justice said March 18.

"The purpose was to make the Cathedral grounds as well as the homeless people who happen to be on those grounds safer."

Bishop Justice is rector of the Cathedral of St. Mary of the Assumption and said the cathedral.

He said it installed the water system about two years ago after learning from "city resources" that such a system was in common use in the city's financial district for "safety, security and cleanliness."

The Archdiocese of San Francisco told CNA that members of the San Francisco Police Department had recommended the system to the cathedral's previous rector.

Bishop Justice said dangerous items such as needles and feces had regularly being left in the cathedral's hidden doorways.

He noted that people who were regularly sleeping in the doorways were informed in advance that the sprinklers were being installed.

"The idea was not to remove those persons, but to encourage them to relocate to other areas of the cathedral, which are protected and safer."

A report from San Francisco KCBS television station quoted a cathedral staff member claiming the sprinkler system had been installed "to keep the homeless from sleeping in the cathedral's doorways."

The sprinkler system ran for about 75 seconds every 30 to 60 minutes.

Reporters saw several homeless people and their belongings getting soaked by the water.

Some were quoted saying the sprinkler system was ineffective at cleaning the area and lacked a drainage system.

Bishop Justice apologized that the cathedral's intentions had been misunderstood and described the sprinkler system method as "ill-conceived."

"It actually has had the opposite effect from what it was intended to do, and for this we are very sorry."

The bishop explained that the Catholic St. Vincent de Paul Society is "the largest supporter of services for the homeless in San Francisco."

"Every year, it helps many thousands of people through food, housing, shelter programs for people at risk including homeless mothers and families, and in countless other ways," Justice said.

"St. Mary's Cathedral is a huge part of that program, and does more than any other Catholic church."

Adding to the cathedral's flak, the first news report on the cathedral water system, the City of San Francisco issued a formal notice that the sprinkler system violates building and safety codes.

Bishop Justice said the archdiocese had already started to remove the system.