"When I decorate my new home, the interior designer quoted me a water and electricity budget of RMB 600,000. Is this a normal price?" "It's the same renovation of an old house of 20 square meters. Why does this company quote RMB 80,000 for water and electricity and that one quotes RMB 150,000? What's the difference?"
This is the most common question we receive in private messages. The decoration is like a level-breaking game without instructions, and the water and electricity project is the ultimate devil hidden in the wall. It is invisible and intangible, but it occupies a large part of the budget, and if it goes wrong, the consequences will be disastrous. Today we will break down how a "healthy and honest" water and electricity budget should be prepared today in 2025, as well as the heart-breaking financial traps.
The golden ratio: How much should your water and electricity budget account for?
First of all, we must have a clear concept of numbers. The total decoration budget is usually divided into four major parts: "design fee", "engineering fee (including demolition, water and electricity, cement work, wood work, paint)", "furniture" and "home appliances".
The cost of water and electricity projects is usually classified as the "Basic Works" item in the "Project Fees". Depending on the age of the house, its proportion of the total budget will fluctuate greatly:
- New houses (within 5 years old): Because the pipelines are still very new, there is usually no need to make major changes. Water and electricity projects (mainly relocation of sockets, installation of lamps, and addition of circuits in conjunction with decoration) account for about 10% ~ 15% of the total budget.
- Medieval house (house age 10-20 years): In this stage of the house, the insulation and materials of the wires and water pipes begin to deteriorate, and professional designers usually recommend partial renewal or whole-house renovation. The water and electricity budget will rise to 15% ~ 20% of the total budget.
- Old house (house more than 20 years old): Congratulations, what you encounter is usually the ultimate version of the Big Devil. The core of old house renovation is "structural safety" and "water and electricity renewal". Almost all old galvanized iron pipes and old lines that do not meet the safety requirements of modern electricity must be replaced. At this time, the budget for hydropower projects may be raised to 20% ~ 25% of the total budget, or even higher.
For example: If your total budget is 2 million and you buy a 30-year-old apartment, then you should probably prepare 400,000 to 500,000 for the water and electricity project. What this money buys is not gorgeous decorations, but the safety of electricity and water for the family for the next 20 years.
Five financial traps that will make you "explode your budget"
After you have the concept of budgeting, you must learn to avoid the favorite "traps" of decorating cockroaches or bad designers. These traps are often disguised as "professional advice", but they are actually trying to empty your wallet.
Trap 1: The necessity of "rewiring the whole house" is exaggerated
This is the most common trick for novices: "The wires provided by the builder are the worst, they must be removed and replaced to be safe!"
Fact check:According to the Ministry of Interior Building Regulations, for new construction projects after 2010, the regulations require that indoor wiring must use "flame-retardant wires and cables" of the National Standard (CNS). In other words, if you buy a new old house or a newly-established house that is nearly 10-15 years old, unless you find that it is using unknown brand wiring, there is no need to change the wiring in the entire house! The correct approach is to ask a plumber to use a "test pen" or "high resistance meter" to check the insulation condition of the line. After confirming that there is no problem, you only need to add new circuits (such as kitchen 220V, independent air-conditioning circuits). If you cut out the wiring changes in the whole room, you may have spent an extra 30,000 to 50,000 in unnecessary money.
Trap 2: "horizontal and vertical" visual aesthetics
After the construction is completed, the master will take you to see the site. The water pipes and electrical pipes on the ground are neatly arranged, and the corners are all beautiful 90-degree right angles. You will feel very satisfied after seeing it and feel that the money was well spent.
Fact check: This "horizontal and vertical" approach, apart from being beautiful, does not contribute to the functionality at all, but is actually a shortcoming! First of all, it uses more than 30% more materials than the "point-to-point" construction method (taking the shortest distance between two points). Secondly, too many 90-degree elbows will make it much more difficult to remove the wires in the future, and may even become a "dead wire" that cannot be removed. The correct construction method is that the pipelines on the ground should take shortcuts to reduce unnecessary bends, because they cannot be seen after the floor is laid, which saves money and is practical.
Trap 3: Strongly promote the "hot water circulation system"
"This way you will have hot water as soon as you turn on the faucet, and you don't have to wait for the cold water to drain out. It's super convenient!" Does this sentence sound exciting?
Fact Check: Hot water recirculating systems are certainly convenient, but they are not suitable for every home. It requires the installation of a return water pump and an extra "return pipe", which will add thousands to tens of thousands in material and installation fees. To make matters worse, in order to maintain the water temperature in the water pipes, the pump will run regularly, which consumes electricity 24 hours a day, and the hot water flows repeatedly in the pipes, which will also cause unnecessary heat loss. For ordinary small families, a more economical solution is to install an "instantaneous electric hot water faucet" (about 2-3,000 yuan) on the bathroom sink, which can solve the problem of hot water for washing hands in winter.
Trap Four: The toilet and balcony are fully waterproofed
To put your mind at ease, the master said: "I will help you waterproof the entire floor of the room, and even the top of the wall, no leaks!"
Fact check: Waterproofing is necessary, but "excessive waterproofing" is just a waste of money. Generally speaking, only the "wet areas" require special reinforcement. For example, in a bathroom, only the wall in the "shower area" needs to be painted to a height of 180 cm or the top, and the walls in other dry areas (such as the sink area and toilet area) can be painted to a height of about 30 cm. If your home does not have a washing machine or sink on the balcony, and is just for drying clothes, the floor can be waterproofed, and there is no need to spend a lot of money on painting the walls. Over-waterproofing a square meter of materials and labor may charge you thousands more, which is really not cost-effective.
Trap 5: Quotation using "one type" pricing
When I got the quotation, I saw "Plumbing and electricity project: one type, 150,000 yuan". When you ask the master for details, he pats his chest and says, "Don't worry, I will help you use the best!"
Fact check: This is the biggest landmine! "One type" is a synonym for ambiguity. A truly conscientious and professional quotation must be broken down into:
- Circuit addition: One additional 110V circuit @ NT$2,500
- Socket relocation: 3 @ NT$800/unit
- Cold water supply outlets: 2 units @ NT$1,500/unit
- Wire brand/specification: Pacific 2.0mm single-core wire
- Water pipe brand/specification: Nanya PVC pipe/stainless steel crimping joint
All materials, construction methods, unit prices, and quantities must be written clearly in black and white in order to avoid finding that the price is completely different from what was "said" at the end of the payment process. Remember to ask for "total price contracting" or "responsible construction", and reserve 10-20% of the final payment for the project, and then pay it off if there are no problems.



