Half of all UK households face the threat of drought restrictions in the new year if rainfall does not return to normal this winter.

Following some of the driest weather on record over the last year, water suppliers urged customers to start making savings to help cope with low levels in reservoirs, rivers and underground aquifers.

The latest appeals by Thames Water and South East Water follow the announcement by Anglian Water this week that it has applied for a drought permit to take emergency supplies out of rivers.

With temperatures in parts of England still exceptionally mild, there is now growing concern about what will happen if – as some forecasters expect – there is a second dry winter in a row.

South East Water said it could not rule out a drought order, and Thames Water indicated that the company needed at least average rainfall this winter to avoid tougher restrictions such as bans on using hosepipes or car washes, and watering sports pitches.

"We had a dry winter and a pretty dry summer: if we have an average winter everything will be fine; if we have a second dry winter things will start to get difficult ... and as any gardener will tell you the ground is still hard," said Richard Aylard, Thames Water's external affairs and sustainability director.

Among the other companies that have been most affected by the exceptionally dry conditions, Severn Trent and Southern Water told the Guardian they are hopeful winter rainfall will help restore supplies enough that further restrictions are not needed next year. Veolia Water Central was more concerned, saying: "We will need very wet weather for the rest of the winter for groundwater levels to recover by next spring. Continuing low rainfall means we could see drought conditions next summer."

Together the six water companies that cover much of central and south-eastern England serve more than 11m of the country's 22m households on the mains water supply.

"For some [companies], a dry winter would not cause resource problems next year; for others, a lack of rain over the next few weeks could lead to a more challenging situation," said Sarah Mukherjee, director of environment for the industry body Water UK. "Many companies will have a better idea in the New Year, as a reasonable amount of rain between then and now could make a significant difference."

The latest drought scenarios follow some of the driest weather since the Met Office records began in 1910, with rainfall in much of central England below 60% of the average for the last year, and much lower than that in some pockets. The mild, dry weather has continued into November in much of the UK, though regions in the north and west have become much wetter and colder.

The Met Office has told government emergency planning groups that there is only a low risk of an exceptionally dry year, however the European Centre for Medium Range Forecasting expects above average pressure over the next few months, which would usually lead to lower rainfall.

In a new approach, Thames Water, the country's biggest water supplier, said it was planning what is thought to be the first poster campaign showing customers the local river their water comes from in a bid to persuade more of them to help protect it while levels are low. Posters showing a pretty-looking stretch of the Kennet will be put up around Marlborough and Swindon in December as part of the push.

The Environment Agency said: "It's not unheard of to have a drought permit issued at this time of year. However, we tend to receive more drought permit applications in spring and summer. The last time one was issued in autumn was 2003. The Environment Agency, water companies and other water users such as farmers and industry have developed plans to cope with prolonged dry spells."

As well as the recent dry weather, water companies and environment regulators are expecting the UK to have more frequent dry winters as a result of climate change. Combined with increasing regulation to force companies to reduce the amount of water they take from rivers to protect wildlife, and growing water use from a rising population, several water companies are planning major infrastructure projects to avoid future water shortages, including the return of major transfers between regions, and new reservoirs. Thames Water has also built a desalination plant to turn briney water from the Thames Estuary into tap water in emergency situations, a technology more commonly associated with parched Middle East countries.