I have a 4wk old boy who loves his food but has...

I have a 4wk old boy who loves his food but has a little trouble with his poos. He is regular though 1 a day always (he is formula fed). Will a little boiled water help him with this? What does it actually do for bubs? Is he too young 4 water yet? How much? Should the water b at rm temp? B4 a feed or after? Or inbetween feeds???????