If you live or own real estate in the Oakland, Berkeley or Piedmont California hills it is important for you to know that you can not stop water, you can only divert it. Properly diverting Water away from your home is the single most important thing you can do to increase the longevity of your foundation. As a Realtor having sold over 140 homes, I explain to Buyers and Sellers that roughly 50% of the water that falls on your property (rain) flows through your downspouts. That much water concentrated in 5 or 6 spots can have a damaging impact on those areas. The water will eventually saturate the soil and the weight of the structure bearing down will eventually lead to the foundation shifting. A shift in the foundation of an older Oakland or Berkeley Hills structure built before steel reinforcement technology will be VERY expensive to fix. The solution… Put splash blocks and/or attach tubes to the bottom of your downspouts. A $50 trip to the Home Depot and diverting the water at least 6 feet away from your foundation is a great start.