In most churches, a stairway near the main entrance led up to a choir loft. Decorations were usually copied from books and applied by native artists. The religious designs and paintings are said to ""show the flavor of the Spanish Era, mixed with the primitive touch of the Indian artists"." The impact that mission architecture has had on the modern buildings of California is readily apparent in the many civic, commercial, and residential structures which exhibit the tile roofs, arched door and window openings, and stuccoed walls that typify the "mission look." These elements are frequently included in the exterior finish of modern buildings in California and the Southwest, and are commonly referred to as Mission Revival Style architecture. The inclusion of these features in whole or part into otherwise ordinary commercial buildings has been met with varying levels of acceptance, and is regarded among some critics as ""mission impossible"", a phenomenon that is seen most brashly in the fast food emporiums of Taco Bell. When well-done, a mission style building will convey an impression of simplicity, permanence, and comfort, with coolness in the heat of the day and warmth in the cold of night (due to a phenomenon known as the thermal flywheel effect). Stone aqueducts, sometimes spanning miles, brought fresh water from a river or spring to the mission site. Baked clay pipes, joined with lime mortar or bitumen, carried the water into reservoirs and gravity-fed fountains, and emptied into waterways where the force of the water would be used to turn grinding wheels, presses, and other simple machinery. Water brought to the mission proper would be used for cooking, cleaning, irrigation of crops, and drinking. Drinking water was allowed to trickle through alternate layers of sand and charcoal to remove the impurities. Influenced by early mission furnishings, "mission oak" furniture bears some similarity to the related Arts and Crafts style furniture, using similar materials but without Arts and Crafts' emphasis on refinement of line and decoration. Oak is the typical material, finished with its natural golden appearance that will age to a rich medium brown color. Components such as legs will often be straight, not tapered, and surfaces will be flat, rather than curved. Generous use of materials leads to heavy and solid furnishings, giving an impression of "groundedness", through simplicity, functionality and stability. Straightforward lines predominate, with little or no decoration, other than that which is incidental to function, such as forged iron hinges and latches.