Wash by hand with a bottle brush and warm soapy water. Because of the small opening in water bottles, dishwashers can not adequately reach and clean the interior. Paint will wear or chip over time in the dishwasher.

Disposable Water Bottles Fill Our Landfill and Waste Resources
Last year Americans tossed over 22 billion empty plastic bottles in the trash.   Bottle production in the US alone drains 1.5 million barrels of oil over the course of one year.  Disposable water bottles  require water and other nonrenewable resources for a single use.

They can leach harmful contaminants:  Studies have shown that disposable (and some reusable) plastic bottles can leach BPA into the water when heated.  Once in the water, BPA can move quickly into people. 
According to the Breast Cancer Fund.  “BPA has been found in blood samples from developing fetuses as well as the surrounding amniotic fluid, and it has been measured in placental tissue and in umbilical cord blood at birth. CDC researchers also found BPA in 95 percent of about 400 urine samples from a broad national sample of adults.   Several studies using both rat and mouse models have demonstrated that even brief exposures to environmentally-relevant doses of BPA during gestation or around the time of birth lead to changes in mammary tissue structure predictive of later development of tumors. Exposure also increased sensitivity to estrogen at puberty. Recent data demonstrate that early exposure to BPA leads to abnormalities in mammary tissue development that are observable even during gestation. Prenatal exposure of rats to BPA also led to increases in the number of pre-cancerous lesions and in situ tumors (carcinomas), and an increased number of mammary tumors following adulthood exposures to a sub-threshold dose (lower than that needed to induce tumors) of a known carcinogen.”

And bottled water is no safer or cleaner than tap:
Tap water is tested more frequently with stricter standards than bottled water.

City tap water must be filtered and disinfected, but there are no federal filtration or disinfection requirements for bottled water.  Tap water must also meet specific standards for toxic chemicals but the bottled water industry is exempt from these regulations.

According to an Environmental Working Group Report in October of 2008, ten tested bottled water brands turned up “an alarming array of contaminants, including cancer-causing byproducts of chlorination, fertilizer residue, industrial solvents and even caffeine.” 

Two of 10 brands tested, Walmart's and Giant's store brands, bore the chemical signature of standard municipal water treatment — a cocktail of chlorine disinfection byproducts, and for Giant water, even fluoride. In other words, this bottled water was chemically indistinguishable from tap water. The only striking difference: the price tag.  In both brands, levels of disinfection byproducts exceeded safety standards established by the state of California and the bottled water industry.”---EWG report Oct 2008

To read the full report:

http://www.ewg.org/reports/bottledwater

Recommendations by the Environmental Working Group, October 2008

• Drink filtered tap water
  Some reports show that up to 44 per cent of bottled water is just tap water – filtered in some cases and untreated in others (O'Rourke, 2008). It has also been noted that bottled water can cost up to 10,000 times more than tap water (Earth Policy Institute, 2006). A carbon filter, whether tap mounted or the pitcher variety, costs a manageable $0.31 per gallon, and removes many of the contaminants found in public tap water supplies; therefore, rendering the water just as good as, if not better than, most brands of bottled water.
• Forgo the plastic bottles
  Plastic additives, many of which have not been fully assessed for safety, have been shown to migrate from the bottles into bottled water to be consumed (Nawrocki 2002). EWG recommends that consumers use a stainless steel bottle filled with filtered tap water to avoid these potentially harmful contaminants.
• Consumers can urge policymakers to improve and adequately fund source water protection programs.  The only long-term solution to our water problem is a clean water supply. This can only be achieved if policymakers enforce more stringent source water protection programs to ensure that our rivers, streams, and groundwater are adequately protected from industrial, agricultural, and urban pollution.