Is my tap water safe to use, if the streets are flooded outside?

Usually: Unless the reservoir or water treatment area is contaminated by flood water, there is no reason to question its safety.

Water safety: Usually the city water is treated before you get it your tap, environmental protection agency oversees this process. It may still have some contaminants but in a acceptable range. Boiling and filtering give some protection not 100%. Bottled waters can not be 100% contaminant free either. The best way to know is contact your water supplier about the local water qualityd

Water: Assume not, until you get the "ALL CLEAR" from disaster relief. So, in preparation for this, have distilled water stored up just in case of emergency.

Here are some...: Despite street flooding, the treated tap water is still best possible source of drinking water supply for most in currently civilized , industrialized society besides the paid bottled water - though still not 100% safe. So, drink it and live on; that is our life reality.

Filtered water: or bottled water is safer to drink for the meantime because of possible contamination in the water due to flooding.

Floods: Floods are New Zealand’s number one hazard in terms of frequency, losses and declared civil defense emergencies. Floods can cause injury and loss of life, damage to property and infrastructure, loss of stock, and contamination of water and land. Getting ready before a flood strikes will help reduce damage to your home and business and help you survive. http://www.getthru.govt.nz/disasters/flood/

Likely yes: Just because there is flooding does not mean that the drinking water has been contaminated. indeed, this, while not impossible, is unlikely. If it did occur, you would immediately receive emergency notifications via TV, phone and radio. I think you are OK drinking.

Maybe: Tap water from municipal water supplies are very safe to drink. Your question might be better answered by asking your water or sewer company.

Filtered water: Tap water is rarely safe given the amount of polonium and radium in the water since the atomic bomb explosions starting in the 1940's. I've a friend who drank city tap water for years who developed radium poisoning which manifest in green rings in the palms of his hands treated with chelators and seaweed pills.

Contact your: local water company if on public water. If on private well I would verify that the well head is not under water and still boil the water to be safe.