Gavin Rossdale and Gwen Stefani bathe together – to avoid wasting water.

Gavin – who has sons Kingston, two, and six-month-old Zuma with his wife Gwen – insists sharing a bathtub with Gwen is a good way to help the environment.

He said: “All families should bathe together. It’s the least they could do!”

The 43-year-old rocker also advises recycling and fitting solar panels to help save energy.

Meanwhile, Gwen, 39, has revealed she and Gavin have a new nickname for Kingston because he is currently going through a troublesome stage.

She said: “Kingston is in that terrible twos. Gavin calls him Sid Vicious. He’s like, ‘You gave birth to Sid Vicious.’”

“He’s definitely got an attitude and Zuma is the opposite. He’s like this cool, laidback, easy-going guy – is that always how it is?”

Kingston has inherited both his parents’ love of music, and already has a keen sense of the songs he wants to hear.

Gwen explained: “He likes Top 40 hits like his mom. Any song that comes on, he’ll get p***ed if you turn the station. He’ll be like, ‘That’s my song! That’s my song!’”

The “No Doubt” singer also revealed her secret to getting back her pre-pregnancy figure – carrying around Zuma.

She laughed: “I have this little chunky baby. Zuma is like the biggest, chunkiest boy. He’s gigantic. He actually gets my arms strong because he weighs so much carrying him around!”

Gwen Stefani is reportedly pregnant with her third child.The singer – who has two sons with husband Gavin Rossdale, Kingston, two, and three-month-old Zuma Nesta Rock – is said to be desperate to increase her brood.

Singer Akon, who worked with Gwen on her 2006 album “The Sweet Escape,” fueled rumors by saying: “I wouldn’t be surprised if she had another in the next couple of months. You saw how quickly she went back for another one.”

The “Right Now (Na Na Na)” singer refused to confirm Gwen is already expecting, but added she is enjoying her role as a parent.

He said: “I know nothing! She definitely loves being a mother, period.”

It was recently revealed Kingston is a huge “flirt” who is massively popular with the girls at the exercise class he attends at West Hollywood’s Fit for Kids.

A source said: “All the little girls in Kingston’s class are enamored of him.”

“He is a total flirt! They are constantly surrounding him, especially at story time. He is very popular.”

Gwen Stefani has given birth to her second child.The “Sweet Escape” singer and rocker husband Gavin Rossdale welcomed new son, Zuma Nesta Rock, into the world yesterday (August 21, 2008) at Los Angeles’ Ceder Senai Medical Center at 12.45pm. He weighed a healthy 8lb 6oz.

Gwen and Gavin – who have another son, Kingston, two – announced the news in a statement, saying: “Kingston, Gwen and Gavin Rossdale welcomed the newest member of their family.”

“Mother, baby and family are all happy and healthy.”

Gwen – who is one of four children – has previously spoken about her desire to have a big family.

Before revealing her pregnancy, the 38-year-old said earlier this year: “I’m in a race to have another.”

Gavin – who Gwen praised as “super into being a dad” – recently revealed he intends to help Gwen as much as possible with the new arrival.

The 42-year-old musician said: “Whatever I can do to help, I’ll do, but the guys get off light.”

“We get to have the fun, then nip off, and the girls have to carry the physical burden of making a human, which is phenomenal.”

As well as Zuma and Kingston, Gavin is also father to 19-year-old model Daisy Lowe, whose mother is British singer Pearl Lowe.