A backup sump pump system protects your basement when the primary pump fails or loses power. Battery backup systems use a marine deep-cycle battery providing 5 to 7 hours of pumping. Water-powered backups use municipal water pressure requiring no electricity. Combination systems offer both primary and backup pumps in one unit. Test your backup system quarterly by unplugging the primary pump. Replace backup batteries every 3 to 5 years for reliable protection during storms.