2000 Ford Focus Owner's Manual - Page 203

Maintenance and care BATTERY Your vehicle is equipped with a Motorcraft maintenance free battery which normally does not require additional water during its life of service. However, for severe usage or in high temperature climates, check the battery electrolyte level. Refer to the Scheduled Maintenance Guide" for the service interval schedules. If the electrolyte level in the battery is low, you can add plain tap water to the battery, as long as you do not use hard water (water with a high mineral or alkali content). If possible, however, try to only fill the battery cells with distilled water. If the battery needs water often, have the charging system checked. Keep the electrolyte level in each cell up the the level indicator". Do not overfill the battery cells. For longer, trouble free operation, keep the top of the battery clean and dry. Also, make certain the battery cables are always tightly fastened to the battery terminals. 203