Although consultancy firm Atkins has been commissioned to produce guidance for water companies on current legislation, the work does not yet include developing a final code of practice.
The HTA and Waterwise have been working together to develop a code, which they have sent to Atkins as their consultation response, including concessions for those who need them and different levels of restriction.
Atkins' consultation closed last week, and HTA policy adviser David Brown warned that immediate action was needed on agreement of a code, which water companies were asked by Defra to develop following the 2006 hosepipe bans.
"We need a code of practice agreed and in place by next spring, and with goodwill on both sides there is no reason we couldn't have something by then," said Brown.
"We need something that is clearly understandable by everyone, including gardeners. We don't want the same thing to happen as in 2006, with different companies bringing in different restrictions."
Majestic Trees managing director Steve McCurdy was forced to lay off staff after the 2006 hosepipe ban slashed sales. He said it was crucial that mistakes were not repeated: "We need to get something done when we are not in a crisis situation and keep up the pressure."
Waterwise director Jacob Tompkins added: "Other water restrictions legislation throughout the world allows the watering of gardens even in times of severe drought. By planning sensible restrictions we can ensure the future of our water supply."
In May, the Government announced it intended to update the legislation on hosepipe bans through the forthcoming Floods and Water Bill.
A Defra representative said work was being done on the draft bill. She said: "The water industry needs to come up with the code of practice before the Bill becomes law, but the legislative process is a very uncertain thing so it wouldn't be sensible for us to take a guess on the time scale."