Sir Denis O'Connor, HM Chief Inspector of Constabulary, said an average of only 11% of officers and police community support officers (PCSOs) are able to meet frontline demands.
He highlighted how in some forces only six in every 100 officers are on a duty visible to the public during peak Friday night hours while larger numbers work quiet Monday mornings.
The former Met assistant commissioner blamed the low availability on the reliance on PCSOs, who do not work after 8pm, as well as shift patterns, risk management, bureaucracy and increased niche posts.
Sir Denis said the findings were further evidence of how the thin blue line must be radically redrawn if forces stand any chance of meeting huge cuts without damage to policing.
His comments came as a series of reports found police in England and Wales could save £1 billion without cutting services, but a massive potential funding gap remains that many forces are not prepared for.
Reports by the Audit Commission, HM Inspectorate of Constabulary and the Wales Audit Office found police could shave £1 billion from central government funding of around £13.7 billion.
Officials said money could be saved by more collaboration between forces, better shift patterns to match demand, cutting back office costs and more efficient procurement of national contracts.
But they warned further cuts will inevitably reduce the number of officers on the beat and responding to emergencies unless there is a "total redesign" of how the police is run and overseen.
Sir Denis warned that one in three forces is not adequately prepared for cuts and that those who spend more money are not necessarily the most effective at tackling crime and reassuring the public.
The former senior officer urged the Government to focus cash on putting officers on the beat and said ministers should consider withholding cash from forces who do not spend it wisely.
Sir Denis cautioned reform will be hampered by the fact police officers cannot be made redundant and it remains unclear whether forces can even make them retire after 30 years' service.
Over the last four years, the number of officers working neighbourhood beats has fallen by 1,429 as more officers are drawn into specialisms for tackling crimes from terrorism to child abuse.
Watchdogs have pointed out how increased bureaucracy and guidelines, created by a raft of organisations, have also pulled officers off the frontline at a time when the public want to see more.
Sir Denis said there is no time for a Royal Commission to review the demands on police, but that senior officers must "rise to the challenge" and tell the public of the hard choice they face.
"The challenge for the police service is to reduce spending without reducing public confidence.
"Our reports shows that while some forces are getting ready for the budget cuts we know are inevitable, many forces have yet to make adequate preparations.
"We are today challenging the police, managers and politicians who make strategic decisions about the future of policing in England and Wales, to use our reports to thoroughly examine their choices so that the public's safety and well-being are not put at risk."
Michael O'Higgins, of the Audit Commission, said: "Better value for money in policing will be a challenge, but it is possible. Many police forces have shown how to save money and actually improve performance while maintaining public confidence - some have even done this with fewer police officers.
"And greater local scrutiny of police spending should help the higher-spending forces."
Paul McKeever, of the Police Federation of England and Wales, said there was such a multitude of ideas being flagged as the possible way forward that forces should not be blamed for not knowing which path to pursue.
"What is needed is a consistent approach to efficiency savings across the 43 forces in England and Wales, driven nationally, but managed locally to ensure chief officers have the flexibility needed to serve different communities in different areas."
Chief Constable Grahame Maxwell, the Association of Chief Police Officers (Acpo) lead on finance and resources, said savings as large as the £1 billion would require "significant re-engineering" to deliver and might require legislative change.
"Eighty per cent of the Police Service budget is made up of people and savings of that extent would therefore have a major impact on numbers," he added.
Rob Garnham, chairman of the Association of Police Authorities, said proposed changes to police accountability were a distraction which could only increase the risk of not achieving the aims highlighted by the reports.
Policing and Criminal Justice Minister Nick Herbert said: "We share the view that the rise in police numbers and resources has not been reflected in increasing visibility, and that there are savings to be made through greater force collaboration, smarter use of the workforce and a reduction in bureaucracy.
"This report shows that, even if resources are tighter, we can still get officers out on to the streets, where the public want to see them. Our reforms to make the police more accountable to their local communities will make sure that happens."
Sir Denis said today that he was confident savings could be made across forces.
"Absolutely, I think they could be," he told the BBC Radio 4 Today programme.
"The fact of the matter is over the years the police have become wrapped up in procedure, guidance and rules, which means they have to do an awful lot of treatment to every crime that goes through the courts. It all builds up and it all costs money."
Comments