I just noticed that the metal part of my Philips sterilizer is rusty. anybody else has this issue? I've only used it for 3 months. is it harmful for baby?

Same as Louis, I used Citric Acid Powder which cost about $3 per pack from Phoon Huat. Remove all the baskets, add water into the metal part, then pour the citric acid powder in, let it boil for 1-2mins and manually switch it off otherwise water will all dry up. Wait for 30-45mims before using a brush to scrub off the dirty things on the metal and clean them off. Must let the sterilizer run without sterilizing bottles at least once. It is recommended to clean at least once per week. Alternatively, you can use fresh lemon too. But personally, I find citric acid powder works better in cleaning the metal part.

It is normal in sterilizers. It is recommended to descale your sterilizer every 1-2 weeks to prevent it from being rusty. You must always unplug and wait for the sterilizer to cool down before descaling. Pour 80ml of white vinegar and 20ml of water into the water reservoir. Leave it there until the limescale dissolves. Pour away the solution and pour in clear water. Pour away the water and wipe the heating plate with damp cloth. Do not rinse it under tap water. In severe case, kiddy palace do sell the agent for descaling.

What you are seeing is limescale deposit. It builds up in appliances when the residue of minerals (naturally contained in water) fail to evaporate when water is heated. Though it is not harmful, it is unsightly, hard to clean and may impair the operation of appliances or damage components if allowed to build up. You can take a look at this document by Philips for instructions on how to do the descaling. https://images-eu.ssl-images-amazon.com/images/I/91wZosFU4sS.pdf

i went Phoon Huat aka Redman and bought a pack of Citric Acid powder. 1 tablespoon to 100ml water. Turn on the steriliser let it boil and after it off. Let it stand for 30 mins. pour away the water and wipe inside dry... no smell after that as compared to the vinegar which i had also tried...

It is stated in the manual on how to clean the metal plate. Any white vinegar will do the trick. Pour water and some vinegar, on the switch and use a brush to scrub when it is bubbling. All the stains will be removed.