The Constitutional Court will have to decide whether Johannesburg's prepaid water meters are legal and whether the government's free water allowance is enough.

Residents of Phiri in Soweto took the issue to court on Wednesday.

The meters were first installed there by the city in 2005 as part of a programme to curb huge losses the city was incurring for non-payment for water supply and to have better control over water usage.

One of the reasons the previous "deemed consumption" system was problematic was because residents said that even if they were "water wise" and cut down on their use, they still paid the same.

The city also could not detect unusually high consumption which could indicate a leak.

But the Phiri residents, who have kept the case bubbling for years as it moved through the High Court in Johannesburg and the Supreme Court of Appeal, say the meters just cut them off after they have used up the free 6kl a month of water the government gives everyone in the country to make sure that at least the poor have some water.

The application is being done in the names of Phiri residents Lindiwe Mazibuko, Grace Munyai, Jennifer Makoatsane, Sophia Malekutu and Vusimusi Paki. Paki has since died.

A number of mostly elderly people were in court in support of their application. With their tweed fedoras and berets they listened quietly, holding their supplied lunch packs and sipping bottles of house-branded water the court has recently started providing.

The residents believe that the meters are illegal because the Water Services Act does not allow water to just be cut off without representations.

They say the recently introduced system of making representations for an indulgence for extra free water, via a visit to a social worker, does not always work. Some people find it demeaning to admit that they are very poor to qualify for indigency allowances.

They argue that the free water allocation should be increased to 50kl for dignified living, given that at least 10 people live on the average Gauteng stand. Since the case started the city has introduced an expanded social services policy, which sets this as the standard for the poorest, but their advocate Wim Trengove said it was not clear yet whether this programme was operational.

Trengove argued that the city was discriminating against them by not offering credit access to water, after the payment of a deposit, like other parts of the city.

"I accept that the problem (of non payment) requires a solution but why did it differ from the solution that applied in white Johannesburg?" asked Trengove.

He said it was wrong that the city had a different policy for different parts of the city on the assumption that some people can be trusted with credit, and others not.

"The worst payers are government institutions and yet they are supplied water on credit."

Justice Kate O'Regan pointed out that between one-quarter and one-third of the city's water was purchased by Soweto residents, with only 1% of users paying for it.

But Trengove said that if someone in Parktown was having a difficult month, their water supply was not simply cut off.

The city's advocate Gilbert Marcus said the meters were legally introduced in terms of bylaws, with consultation with the community, and a 99% uptake.

When a meter started running out of money, there was a visual warning and a physical warning in that water flow became intermittent.

People who have the credit access face harsher treatment when in arrears: their electricity cut off, they lose their deposit, have to pay a reconnection charge, pay a new higher deposit, and pay a penalty.

They may also be referred for debt collection or blacklisting.

He said that the issue for Phiri residents was not about being cut off, it was about using up their free water allocation.

He rejected a racial prejudice element saying that the meters were being introduced in new developments like Cosmo City, a housing development to the west of Johannesburg that caters to different incomes.

The Water Affairs Department said that the Constitution guaranteed access to water and food, but it did not quantify this.

If the court set down a water minimum, they may soon have to do that for food too, said advocate Patrick Mtshaulana.

Rather, the court should consider the progressions that government was making in meeting people's needs as well as how the city balanced a whole range of services for its people, and that people in some parts of the country were even worse off.

Judgement was reserved.