Members of Parliament (MPs) on Wednesday resolved to forge ahead with a full-scale parliamentary inquiry into the collapse of the water and sanitation department.

In a joint meeting of the water and sanitation portfolio committee and the standing committee on public accounts (Scopa), MPs decided to engage the Auditor General (AG) and National Treasury (NT) to work out the scope of the probe into the department, which is broke and has a R2.9-billion overdraft facility with the Reserve Bank.

"We are seeking to understand what it is in within the internal process of the department that led to this situation, so our engagement with the AG as well as with NT and looking at the BRRR [Budget Review and Recommendations report] as well as Scopa and the Special Investigating Unit because they apparently briefed the portfolio committee, let's see if we can also get them to assist us in isolating the issues," said Scopa chairperson Themba Godi.

The committee decided on bringing on board an evidence leader to ensure witnesses testify under oath. Certain MPs will be given specific tasks of "zooming into issues" and would be able to weigh in on the cross-examination style questioning of witnesses.

Inkatha Freedom Party MP Mkhuleko Hlengwa said engaging the Auditor General was key to uncovering how far back they go when probing the collapse of the department.

"I was very deliberate in saying let's engage the AG. The AG is best placed to say when the camel's back broke," he said.

Democratic Alliance MP Leon Basson said public participation in the inquiry would be key.

"We must realise that it's not just about money. It's about the life of people - water - and if we miss out on this opportunity to clean up this department, we won't get a second chance or second bite on it. It must be as open as possible," said Basson.

"Anyone with information must come forward...even if it takes us much longer than any other process because when we leave this Parliament for the next Parliament, we must give a clean department that can deliver water and services to the community."

Water and sanitation portfolio committee chairperson Mlungisi Johnson told MPs that while a formal report would be tabled in the National Assembly following the inquiry, they would not wait for the completion of this before engaging law enforcement agencies if any corruption or any other wrongdoing is uncovered.

"If we have any concrete case, we should lodge it in any police station. That process must for sure take its own turn without having to wait for this particular process," said Johnson.

MPs will meet with the AG and NT in the next two weeks before the inquiry's terms of reference is finalised.