It was reported yesterday (after I had posted my take on this topic) on China.org.cn that

The Environmental Protection Agency in Chengdu has taken emergency measures to ensure safe drinking water. They are coping with contamination in Zi Pingpu reservoir, Chengdu's major water source of drinking water.

Ma Ning, director of the Environmental Protection Supervision Center in SW China, told Beijing News that petroleum materials found in the reservoir water have surpassed set safety standards. Apparently, boats used for rescue work discharged these harmful substances.

I find it a little hard to believe that "rescue boats" were responsible for all of the petroleum contamination in this reservoir. A more likely source I suspect is ruptured petroleum pipelines or storage tanks, but at this point, the source (assuming it has been identified and stopped), is not particularly relevant.

Despite the fact the this reservoir is Chengdu's major source of drinking water, Mr. Ning
assured the public that the drinking water in Chengdu wouldn't be contaminated because the Zi Pingpu reservoir is located 45 kilometers from the biggest waterworks, the No. 6 waterworks located in Pixian County and servicing Chengdu City. His statement was confirmed by the monitoring data from the waterworks, which indicated that petroleum material contained in water registered at 0.03mg/l - lower than the officially designated safety standard of 0.05mg/l.

I find this point a little confusing. I don't think that Mr. Ma is making the contention that somehow the petroleum contaminated water will remediate itself on its 45 kilometer journey to the waterworks. Perhaps he means that the first slug of contaminated water has not yet reached the waterworks.

To address the pollution in the Zi Pinghu reservoir
the No. 6 waterworks has been asked to keep adequate water purification materials on hand such as active carbon, potassium permanganate and potassium perchlorate. This cache guarantees adequate water purification measures so that municipal drinking water meets the safety standards.

I'm not an expert on drinking water treatment (there is a good primer here), but I would suspect that only the active carbon would be effective to help remove the "petroleum materials." Potassium permanganate (KMnO4)
is used primarily to control taste and odors, remove color, control biological growth in treatment plants, and remove iron and manganese. In a secondary role, potassium permanganate may be useful in controlling the formation of THMs and other DBPs [disinfection by-products] by oxidizing precursors and reducing the demand for other disinfectants.

I confess I don't know what potassium perchlorate is used for in the water treatment process. All the information I found talked about treatment methods for removing potassium perchlorate from drinking water.

Finally,

In addition to these measures, the center also warned local governments to carefully monitor how they use disinfectants in disaster-hit areas, especially the chemical product Panaplate.

Panaplate is apparently a trade name for

Dichlorvos (2,2-dichlorovinyl dimethyl phosphate), or DDVP is a highly volatile organophosphate, widely used as a fumigant to control household, public health, and stored product insects. It is effective against mushroom flies, aphids, spider mites, caterpillars, thrips, and whiteflies in greenhouse, outdoor fruit, and vegetable crops, and also for the milling and grain handling industries. Dichlorvos is used to treat a variety of parasitic worm infections in dogs, livestock, and humans, and can be fed to livestock to control bot fly larvae in the manure. It acts against insects as both a contact and a stomach poison. It is available as an aerosol and soluble concentrate. It is also used as a household pesticide, typically encountered in the form of pet collars and "no-pest strips" of pesticide-impregnated plastic. The United States Environmental Protection Agency first considered a ban on DDVP in 1981. Since then it has been close to being banned on several occasions, but continues to be available; concerns are primarily over acute and chronic toxicity, as there is no conclusive evidence of carcinogenicity to date.

I will not offer any advice (don't want to start any rumors), but I leave it to each reader to decide whether they will drink the tap water in Chengdu.

As a final note, it is good to see the "regional center" of the Ministry of Environmental Protection involved in a high profile way in this situation. I hope that this will enhance the stature of these centers throughout China.