But, in her address to big business on the water crisis this week, the mayor reiterated the municipality's commitment at keeping a bull-blown water emergency at bay.
The city council would later this month debate on raising water restrictions to Level 4, which is just one level below the emergency tier.
De Lille said the city had made available R22 million for "first first line response teams" which would accelerate response times to reported water faults.
An additional R315 million had been budgeted for emergency schemes over a period of three financial years.
Cape Town's collective dam levels have continued dipping and were at an effective 12% this week.
"We are heading for trying times as we are already in May and we have yet to see the spells of continual rain which we are accustomed to at this time of the year," the mayor said at the gathering on Tuesday night.
"Climate change means there is no more normal – we have seen that the rains will not come as it used to with our lowest rainfall on record in 100 years over the past two winters."
De Lille urged the municipality's four million consumers that "there has to be a drastic change in our behaviour and water use".
"Moving towards becoming a water sensitive city means managing all urban water, (including) stormwater, groundwater, rivers and treated wastewater effluent, in an integrated way, with the ultimate aim of being able to use these as sources of drinking water," she said.
De Lille added the city was reviewing its 30-year water plan "to give greater consideration to climate change so that we can to see a shift where Cape Town will become a water-sensitive city".
The mayor also acknowledged businesses which she said were displaying a positive attitude in light of the water crisis.
"The Tsogo Sun group, like the City, has endorsed and shared the Cape Argus 'Drip Drop' song which can be used as a fun way of keeping showers to two and a half minutes (and the song) has been shared by hundreds of thousands of social media users," De Lille said.
To save water, Airports Company of South Africa (ACSA) had also reported it ran water campaigns, had indigenous landscaping, used low flush sensors in bathrooms, and that all car washes used recycled water.
"We are now also calling on residents and businesses to stop using municipal water for all outside use such as watering gardens or filing up pools and that those who are able to do so invest in greywater and rainwater harvesting, among others, for all non-potable uses," De Lille said.
Level 4 water restrictions are expected to come into effect from the beginning of next month.