Paint requires special disposal practices. These products must never be poured down storm drains, drains, the household sink (especially if you have a septic tank) or onto the ground. Paints can be recycled see below for more information.
This article on Paint and Waterways Pollution has some useful suggestions for cleaning up after your painting session.
Paint for interior and exterior projects, thinners, turpentine, mineral spirits and solvents.
Standard household paints are typically a smooth blend of toxic chemicals: including pigment (the colour) carried by a resin and/or binder, a solvent to help the paint application, and a dryer. In vinyl and acrylic paints they will also include plastics compounds. Some will include formaldehyde, arsenic, thinners, and foamers.
This Ministry for the Environment article highlights some issues and lists some useful resources and information as well.
To reduce paint waste, only buy what you need. Carefully measure the area to paint and use the coverage recommendations on the paint label or seek advice from your paint supplier.
There are alternatives to using paint: use an oil or wax to bring out the natural colours of timber; look for natural or eco-paints that are non-toxic (e.g. Natural Paints).
For interior use: decorative and easy to remove wall-stickers, place a folding screen in front of a blank wall to add colour and focus, hang up fabric or wallpaper panels.
Keep leftover paint for touch-ups and small projects.
Add another coat to your paint finish for extra protection.
Use for creating signs and banners.
Store it, as paint can last for years: cover with plastic wrap, place lid on securely and store upside down (out of reach from children).
Empty paint cans can be reused as paint pots. Paint pails as weed or rubbish buckets.
Resene Colourshop cnr Ridgway and Wilson Streets is part of the Resene Paintwise programme. If you have leftover paint, Resene will take it back for recycling any time. Paint cans/pails need to be in good condition and labelled correctly according to their contents as the type of paint - solvent-based or acrylic - needs to be identifiable.
On Fridays, Resene will accept any other brand of paint for the small fee of 15 cents per litre (charged according to the capacity of the can/pail regardless of volume of paint). On the last Friday of the month this service is free thanks to an agreement Resene Colourshop has with Whanganui District Council.
If you do not have access to reuse or recycling options, unwanted paint is accepted at the hazardous waste shed at the local transfer station. Thinners, solvents and turpentine can be disposed of at the hazardous waste shed too.